[33] _Stannum_, as a term for lead-silver alloys, is a term which

Agricola (_De Natura Fossilium_, pp. 341-3) adopted from his views of

Pliny. In the _Interpretatio_ and the Glossary he gives the German

equivalent as _werk_, which would sufficiently identify his meaning were

it not obvious from the context. There can be little doubt that Pliny

uses the term for lead alloys, but it had come into general use for tin

before Agricola's time. The Roman term was _plumbum candidum_, and as a

result of Agricola's insistence on using it and _stannum_ in what he

conceived was their original sense, he managed to give considerable

confusion to mineralogic literature for a century or two. The passages

from Pliny, upon which he bases his use, are (XXXIV, 47): "The metal

which flows liquid at the first melting in the furnace is called

_stannum_, the second melting is silver," etc. (XXXIV, 48): "When copper

vessels are coated with _stannum_ they produce a less disagreeable

flavour, and it prevents verdigris. It is also remarkable that the

weight is not increased.... At the present day a counterfeit _stannum_

is made by adding one-third of white copper to tin. It is also made in

another way, by mixing together equal parts of tin and lead; this last

is called by some _argentarium_.... There is also a composition called

_tertiarium_, a mixture of two parts of lead and one of tin. Its price

is twenty _denarii_ per pound, and it is used for soldering pipes.

Persons still more dishonest mix together equal parts of _tertiarium_

and tin, and calling the compound _argentarium_, when it is melted coat

articles with it." Although this last passage probably indicates that

_stannum_ was a tin compound, yet it is not inconsistent with the view

that the genuine _stannum_ was silver-lead, and that the counterfeits

were made as stated by Pliny. At what period the term _stannum_ was

adopted for tin is uncertain. As shown by Beckmann (Hist. of Inventions

II, p. 225), it is used as early as the 6th century in occasions where

tin was undoubtedly meant. We may point out that this term appears

continuously in the official documents relating to Cornish tin mining,

beginning with the report of William de Wrotham in 1198.

[34] The Latin term for litharge is _spuma argenti_, spume of silver.

[35] Pliny, XXXIII, 35. This quotation is given in full in the footnote

p. 466. Agricola illustrates these "tubes" of litharge on p. 481.

[36] Assuming Roman weights, three _unciae_ and three _drachmae_ per

_centumpondium_ would be about 82 ozs., and the second case would equal

about 85 ozs. per short ton.

[37] Agricola uses throughout _De Re Metallica_ the term _molybdaena_

for this substance. It is obvious from the context that he means

saturated furnace bottoms--the _herdpley_ of the old German

metallurgists--and, in fact, he himself gives this equivalent in the

_Interpretatio_, and describes it in great detail in _De Natura

Fossilium_ (p. 353). The derivatives coined one time and another from

the Greek _molybdos_ for lead, and their applications, have resulted in

a stream of wasted ink, to which we also must contribute. Agricola chose

the word _molybdaena_ in the sense here used from his interpretation of

Pliny. The statements in Pliny are a hopeless confusion of _molybdaena_

and _galena_. He says (XXXIII, 35): "There are three varieties of it

(litharge)--the best-known is _chrysitis_; the second best is called

_argyritis_; and a third kind is called _molybditis_.... _Molybditis_ is

the result of the smelting of lead.... Some people make two kinds of

litharge, which they call _scirerytis_ and _peumene_; and a third

variety being _molybdaena_, will be mentioned with lead." (XXXIV, 53):

"_Molybdaena_, which in another place I have called _galena_, is an ore

of mixed silver and lead. It is considered better in quality the nearer

it approaches to a golden colour and the less lead there is in it; it is

also friable and moderately heavy. When it is boiled with oil it becomes

liver-coloured, adheres to the gold and silver furnaces, and in this

state it is called _metallica_." From these two passages it would seem

that _molybdaena_, a variety of litharge, might quite well be

hearth-lead. Further (in XXXIV, 47), he says: "The metal which flows

liquid at the first melting in the furnace is called _stannum_, at the

second melting is silver, that which remains in the furnace is

_galena_." If we still maintain that _molybdaena_ is hearth-lead, and

_galena_ is its equivalent, then this passage becomes clear enough, the

second melting being cupellation. The difficulty with Pliny, however,

arises from the passage (XXXIII, 31), where, speaking of silver ore, he

says: "It is impossible to melt it except with lead ore, called

_galena_, which is generally found next to silver veins." Agricola

(_Bermannus_, p. 427, &c.), devotes a great deal of inconclusive

discussion to an attempt to reconcile this conflict of Pliny, and also

that of Dioscorides. The probable explanation of this conflict arises in

the resemblance of cupellation furnace bottoms to lead carbonates, and

the native _molybdaena_ of Dioscorides; and some of those referred to by

Pliny may be this sort of lead ores. In fact, in one or two places in

Book IX, Agricola appears to use the term in this sense himself. After

Agricola's time the term _molybdaenum_ was applied to substances

resembling lead, such as graphite, and what we now know as _molybdenite_

(_MoS_{2}_). Some time in the latter part of the 18th century, an

element being separated from the latter, it was dubbed _molybdenum_, and

confusion was five times confounded.

[38] Agricola here refers to the German word used in this connection,

_i.e._, _hundt_, a dog.

[39] If Agricola means the German _centner_, this charge would be from

about 4.6 to 5.7 short tons. If he is using Roman weights, it would be

from about 3 to 3.7 short tons.

[40] The refining of silver in "tests" (Latin _testa_) is merely a

second cupellation, with greater care and under stronger blast. Stirring

the mass with an iron rod serves to raise the impurities which either

volatilize as litharge or, floating to the edges, are absorbed into the

"test." The capacity of the tests, from 15 _librae_ to 50 _librae_,

would be from about 155 to 515 ozs. Troy.

[41] A _drachma_ of impurities in a _bes_, would be one part in 64, or

984.4 fine. A loss of a _sicilicus_ of silver to the _bes_, would be one

part in 32, or about 3.1%; three _drachmae_ would equal 4.7%, and half

an _uncia_ 6.2%, or would indicate that the original bullion had a

fineness in the various cases of about 950, 933, and 912.

[42] _Praefectus Regis_.

BOOK XI.

Different methods of parting gold from silver, and, on the other hand,

silver from gold, were discussed in the last book; also the separation

of copper from the latter, and further, of lead from gold as well as

from silver; and, lastly, the methods for refining the two precious

metals. Now I will speak of the methods by which silver must be

separated from copper, and likewise from iron.[1]

[Illustration 493 (Building Plan for Refinery): Six long walls: A--The

first. B--The first part of the second. C--The further part of the

second. D--The third. E--The fourth. F--The fifth. G--The sixth.

Fourteen transverse walls: H--The first. I--The second. K--The third.

L--The fourth. M--The fifth. N--The sixth. O--The seventh. P--The

eighth. Q--The ninth. R--The tenth. S--The eleventh. T--The twelfth.

V--The thirteenth. X--The fourteenth.]

The _officina_, or the building necessary for the purposes and use of

those who separate silver from copper, is constructed in this manner.

First, four long walls are built, of which the first, which is parallel

with the bank of a stream, and the second, are both two hundred and

sixty-four feet long. The second, however, stops at one hundred and

fifty-one feet, and after, as it were, a break for a length of

twenty-four feet, it continues again until it is of a length equal to

the first wall. The third wall is one hundred and twenty feet long,

starting at a point opposite the sixty-seventh foot of the other walls,

and reaching to their one hundred and eighty-sixth foot. The fourth

wall is one hundred and fifty-one feet long. The height of each of these

walls, and likewise of the other two and of the transverse walls, of

which I will speak later on, is ten feet, and the thickness two feet and

as many palms. The second long wall only is built fifteen feet high,

because of the furnaces which must be built against it. The first long

wall is distant fifteen feet from the second, and the third is distant

the same number of feet from the fourth, but the second is distant

thirty-nine feet from the third. Then transverse walls are built, the

first of which leads from the beginning of the first long wall to the

beginning of the second long wall; and the second transverse wall from

the beginning of the second long wall to the beginning of the fourth

long wall, for the third long wall does not reach so far. Then from the

beginning of the third long wall are built two walls--the one to the

sixty-seventh foot of the second long wall, the other to the same point

in the fourth long wall. The fifth transverse wall is built at a

distance of ten feet from the fourth transverse wall toward the second

transverse wall; it is twenty feet long, and starts from the fourth

long wall. The sixth transverse wall is built also from the fourth long

wall, at a point distant thirty feet from the fourth transverse wall,

and it extends as far as the back of the third long wall. The seventh

transverse wall is constructed from the second long wall, where this

first leaves off, to the third long wall; and from the back of the third

long wall the eighth transverse wall is built, extending to the end of

the fourth long wall. Then the fifth long wall is built from the seventh

transverse wall, starting at a point nineteen feet from the second long

wall; it is one hundred and nine feet in length; and at a point

twenty-four feet along it, the ninth transverse wall is carried to the

third end of the second long wall, where that begins again. The tenth

transverse wall is built from the end of the fifth long wall, and leads

to the further end of the second long wall; and from there the eleventh

transverse wall leads to the further end of the first long wall. Behind

the fifth long wall, and five feet toward the third long wall, the sixth

long wall is built, leading from the seventh transverse wall; its length

is thirty-five feet, and from its further end the twelfth transverse

wall is built to the third long wall, and from it the thirteenth

transverse wall is built to the fifth long wall. The fourteenth

transverse wall divides into equal parts the space which lies between

the seventh transverse wall and the twelfth.

The length, height, breadth, and position of the walls are as above.

Their archways, doors, and openings are made at the same time that the

walls are built. The size of these and the way they are made will be

much better understood hereafter. I will now speak of the furnace hoods

and of the roofs. The first side[2] of the hood stands on the second

long wall, and is similar in every respect to those whose structure I

explained in Book IX, when I described the works in whose furnaces are

smelted the ores of gold, silver, and copper. From this side of the hood

a roof, which consists of burnt tiles, extends to the first long wall;

and this part of the building contains the bellows, the machinery for

compressing them, and the instruments for inflating them. In the middle

space, which is situated between the second and third transverse walls,

an upright post eight feet high and two feet thick and wide, is erected

on a rock foundation, and is distant thirteen feet from the second long

wall. On that upright post, and in the second transverse wall, which has

at that point a square hole two feet high and wide, is placed a beam

thirty-four feet and a palm long. Another beam, of the same length,

width, and thickness, is fixed on the same upright post and in the third

transverse wall. The heads of those two beams, where they meet, are

joined together with iron staples. In a similar manner another post is

erected, at a distance of ten feet from the first upright post in the

direction of the fourth wall, and two beams are laid upon it and into

the same walls in a similar way to those I have just now described. On

these two beams and on the fourth long wall are fixed seventeen

cross-beams, forty-three feet and three palms long, a foot wide, and

three palms thick; the first of these is laid upon the second transverse

wall, the last lies along the third and fourth transverse walls; the

rest are set in the space between them. These cross-beams are three feet

apart one from the other.

In the ends of these cross-beams, facing the second long wall, are

mortised the ends of the same number of rafters reaching to those

timbers which stand upright on the second long wall, and in this manner

is made the inclined side of the hood in a similar way to the one

described in Book IX. To prevent this from falling toward the vertical

wall of the hood, there are iron rods securing it, but only a few,

because the four brick chimneys which have to be built in that space

partly support it. Twelve feet back are likewise mortised into the

cross-beams, which lie upon the two longitudinal beams and the fourth

long wall, the lower ends of as many rafters, whose upper ends are

mortised into the upper ends of an equal number of similar rafters,

whose lower ends are mortised to the ends of the beams at the fourth

long wall. From the first set of rafters[4] to the second set of rafters

is a distance of twelve feet, in order that a gutter may be well placed

in the middle space. Between these two are again erected two sets of

rafters, the lower ends of which are likewise mortised into the beams,

which lie on the two longitudinal beams and the fourth long wall, and

are interdistant a cubit. The upper ends of the ones fifteen feet long

rest on the backs of the rafters of the first set; the ends of the

others, which are eighteen feet long, rest on the backs of the rafters

of the second set, which are longer; in this manner, in the middle of

the rafters, is a sub-structure. Upon each alternate cross-beam which is

placed upon the two longitudinal beams and the fourth long wall is

erected an upright post, and that it may be sufficiently firm it is

strengthened by means of a slanting timber. Upon these posts is laid a

long beam, upon which rests one set of middle rafters. In a similar

manner the other set of middle rafters rests on a long beam which is

placed upon other posts. Besides this, two feet above every cross-beam,

which is placed on the two longitudinal beams and the fourth long wall,

is placed a tie-beam which reaches from the first set of middle rafters

to the second set of middle rafters; upon the tie-beams is placed a

gutter hollowed out from a tree. Then from the back of each of the first

set of middle rafters a beam six feet long reaches almost to the gutter;

to the lower end of this beam is attached a piece of wood two feet long;

this is repeated with each rafter of the first set of middle rafters.

Similarly from the back of each rafter of the second set of middle

rafters a little beam, seven feet long, reaches almost to the gutter; to

the lower end of it is likewise attached a short piece of wood; this is

repeated on each rafter of the second set of middle rafters. Then in the

upper part, to the first and second sets of principal rafters are

fastened long boards, upon which are fixed the burnt tiles; and in the

same manner, in the middle part, they are fastened to the first and

second sets of middle rafters, and at the lower part to the little beams

which reach from each rafter of the first and second set of middle

rafters almost to the gutter; and, finally, to the little boards

fastened to the short pieces of wood are fixed shingles of pine-wood

extending into the gutter, so that the violent rain or melted snow may

not penetrate into the building. The substructures in the interior which

support the second set of rafters, and those on the opposite side which

support the third, being not unusual, I need not explain.

In that part of the building against the second long wall are the

furnaces, in which exhausted liquation cakes which have already been

"dried" are smelted, that they may recover once again the appearance and

colour of copper, inasmuch as they really are copper. The remainder of

the room is occupied by the passage which leads from the door to the

furnaces, together with two other furnaces, in one of which the whole

cakes of copper are heated, and in the other the exhausted liquation

cakes are "dried" by the heat of the fire.

Likewise, in the room between the third and seventh[5] transverse walls,

two posts are erected on rock foundation; both of them are eight feet

high and two feet wide and thick. The one is at a distance of thirteen

feet from the second long wall; the other at the same distance from the

third long wall; there is a distance of thirteen feet between them. Upon

these two posts and upon the third transverse wall are laid two

longitudinal beams, forty-one feet and one palm long, and two feet wide

and thick. Two other beams of the same length, width, and thickness are

laid upon the upright posts and upon the seventh transverse wall, and

the heads of the two long beams, where they meet, are joined with iron

staples. On these longitudinal beams are again placed twenty-one

transverse beams, thirteen feet long, a foot wide, and three palms

thick, of which the first is set on the third transverse wall, and the

last on the seventh transverse wall; the rest are laid in the space

between these two, and they are distant from one another three feet.

Into the ends of the transverse beams which face the second long wall,

are mortised the ends of the same number of rafters erected toward the

upright posts which are placed upon the second long wall, and in this

manner is made the second inclined side wall of the hood. Into the ends

of the transverse beams facing the third long wall, are mortised the

ends of the same number of rafters rising toward the rafters of the

first inclined side of the second hood, and in this manner is made the

other inclined side of the second hood. But to prevent this from falling

in upon the opposite inclined side of the hood, and that again upon the

opposite vertical one, there are many iron rods reaching from some of

the rafters to those opposite them; and this is also prevented in part

by means of a few tie-beams, extending from the back of the rafters to

the back of those which are behind them. These tie-beams are two palms

thick and wide, and have holes made through them at each end; each of

the rafters is bound round with iron bands three digits wide and half a

digit thick, which hold together the ends of the tie-beams of which I

have spoken; and so that the joints may be firm, an iron nail, passing

through the plate on both sides, is driven through the holes in the ends

of the beams. Since one weight counter-balances another, the rafters on

the opposite hoods cannot fall. The tie-beams and middle posts which

have to support the gutters and the roof, are made in every particular

as I stated above, except only that the second set of middle rafters are

not longer than the first set of middle rafters, and that the little

beams which reach from the back of each rafter of the second set of

middle rafters nearly to the gutter are not longer than the little beams

which reach from the back of each rafter of the first set of middle

rafters almost to the gutter. In this part of the building, against the

second long wall, are the furnaces in which copper is alloyed with lead,

and in which "slags" are re-smelted. Against the third long wall are the

furnaces in which silver and lead are liquated from copper. The interior

is also occupied by two cranes, of which one deposits on the ground the

cakes of copper lifted out of the moulding pans; the other lifts them

from the ground into the second furnace.

On the third and the fourth long walls are set twenty-one beams eighteen

feet and three palms long. In mortises in them, two feet behind the

third long wall, are set the ends of the same number of rafters erected

opposite to the rafters of the other inclined wall of the second furnace

hood, and in this manner is made the third inclined wall, exactly

similar to the others. The ends of as many rafters are mortised into

these beams where they are fixed in the fourth long wall; these rafters

are erected obliquely, and rest against the backs of the preceding ones

and support the roof, which consists entirely of burnt tiles and has the

usual substructures. In this part of the building there are two rooms,

in the first of which the cakes of copper, and in the other the cakes of

lead, are stored.

In the space enclosed between the ninth and tenth transverse walls and

the second and fifth long walls, a post twelve feet high and two feet

wide and thick is erected on a rock foundation; it is distant thirteen

feet from the second long wall, and six from the fifth long wall. Upon

this post and upon the ninth transverse wall is laid a beam thirty-three

feet and three palms long, and two palms wide and thick. Another beam,

also of the same length, width and thickness, is laid upon the same post

and upon the tenth transverse wall, and the ends of these two beams

where they meet are joined by means of iron staples. On these beams and

on the fifth long wall are placed ten cross-beams, eight feet and three

palms long, the first of which is placed on the ninth transverse wall,

the last on the tenth, the remainder in the space between them; they are

distant from one another three feet. Into the ends of the cross-beams

facing the second long wall, are mortised the ends of the same number of

rafters inclined toward the posts which stand vertically upon the second

long wall. This, again, is the manner in which the inclined side of the

furnace hood is made, just as with the others; at the top where the

fumes are emitted it is two feet distant from the vertical side. The

ends of the same number of rafters are mortised into the cross-beams,

where they are set in the fifth long wall; each of them is set up

obliquely and rests against the back of one of the preceding set; they

support the roof, made of burnt tiles. In this part of the building,

against the second long wall, are four furnaces in which lead is

separated from silver, together with the cranes by means of which the

domes are lifted from the crucibles.

In that part of the building which lies between the first long wall and

the break in the second long wall, is the stamp with which the copper

cakes are crushed, and the four stamps with which the accretions that

are chipped off the walls of the furnace are broken up and crushed to

powder, and likewise the bricks on which the exhausted liquation cakes

of copper are stood to be "dried." This room has the usual roof, as also

has the space between the seventh transverse wall and the twelfth and

thirteenth transverse walls.

[Illustration 499 (Hearths for melting lead cakes): A--Hearth. B--Rocks

sunk into the ground. C--Walls which protect the fourth long wall from

damage by fire. D--Dipping-pot. E--Masses of lead. F--Trolley. G--Its

wheels. H--Crane. I--Tongs. K--Wood. L--Moulds. M--Ladle. N--Pick.

O--Cakes.]

At the sides of these rooms are the fifth, the sixth, and the third long

walls. This part of the building is divided into two parts, in the first

of which stand the little furnaces in which the artificer assays metals;

and the bone ash, together with the other powders, are kept here. In the

other room is prepared the powder from which the hearths and the

crucibles of the furnaces are made. Outside the building, at the back of

the fourth long wall, near the door to the left as you enter, is a

hearth in which smaller masses of lead are melted from large ones, that

they may be the more easily weighed; because the masses of lead, just as

much as the cakes of copper, ought to be first prepared so that they can

be weighed, and a definite weight can be melted and alloyed in the

furnaces. To begin with, the hearth in which the masses of lead are

liquefied is six feet long and five wide; it is protected on both sides

by rocks partly sunk into the earth, but a palm higher than the hearth,

and it is lined in the inside with lute. It slopes toward the middle and

toward the front, in order that the molten lead may run down and flow

out into the dipping-pot. There is a wall at the back of the hearth

which protects the fourth long wall from damage by the heat; this wall,

which is made of bricks and lute, is four feet high, three palms thick,

and five feet long at the bottom, and at the top three feet and two

palms long; therefore it narrows gradually, and in the upper part are

laid seven bricks, the middle ones of which are set upright, and the end

ones inclined; they are all thickly coated with lute. In front of the

hearth is a dipping-pot, whose pit is a foot deep, and a foot and three

palms wide at the top, and gradually narrows. When the masses of lead

are to be melted, the workman first places the wood in the hearth so

that one end of each billet faces the wall, and the other end the

dipping-pot. Then, assisted by other workmen, he pushes the mass of lead

forward with crowbars on to a low trolley, and draws it to the crane.

The trolley consists of planks fastened together, is two and one-half

feet wide and five feet long, and has two small iron axles, around which

at each end revolve small iron wheels, two palms in diameter and as many

digits wide. The trolley has a tongue, and attached to this is a rope,

by which it is drawn to the crane. The crane is exactly similar to those

in the second part of the works, except that the crane-arm is not so

long. The tongs in whose jaws[6] the masses of lead are seized, are two

feet a palm and two digits long; both of the jaws, when struck with a

hammer, impinge upon the mass and are driven into it. The upper part of

both handles of the tongs are curved back, the one to the right, the

other to the left, and each handle is engaged in one of the lowest links

of two short chains, which are three links long. The upper links are

engaged in a large round ring, in which is fixed the hook of a chain let

down from the pulley of the crane-arm. When the crank of the crane is

turned, the mass is lifted and is carried by the crane-arm to the hearth

and placed on the wood. The workmen wheel up one mass after another and

place them in a similar manner on the wood of the hearth; masses which

weigh a total of about a hundred and sixty _centumpondia_[7] are usually

placed upon the wood and melted at one time. Then a workman throws

charcoal on the masses, and all are made ready in the evening. If he

fears that it may rain, he covers it up with a cover, which may be moved

here and there; at the back this cover has two legs, so that the rain

which it collects may flow down the slope on to the open ground. Early

in the morning of the following day, he throws live coals on the

charcoal with a shovel, and by this method the masses of lead melt, and

from time to time charcoal is added. The lead, as soon as it begins to

run into the dipping-pot, is ladled out with an iron ladle into copper

moulds such as the refiners generally use. If it does not cool

immediately he pours water over it, and then sticks the pointed pick

into it and pulls it out. The pointed end of the pick is three palms

long and the round end is two digits long. It is necessary to smear the

moulds with a wash of lute, in order that, when they have been turned

upside down and struck with the broad round end of the pick, the cakes

of lead may fall out easily. If the moulds are not washed over with the

lute, there is a risk that they may be melted by the lead and let it

through. Others take hold of a billet of wood with their left hand, and

with the heavy lower end of it they pound the mould, and with the right

hand they stick the point of the pick into the cake of lead, and thus

pull it out. Then immediately the workman pours other lead into the

empty moulds, and this he does until the work of melting the lead is

finished. When the lead is melted, something similar to litharge is

produced; but it is no wonder that it should be possible to make it in

this case, when it used formerly to be produced at Puteoli from lead

alone when melted by a fierce fire in the cupellation furnace.[8]

Afterward these cakes of lead are carried into the lead store-room.

[Illustration 501 (Stamp-mill for breaking copper cakes): A--Block of

wood. B--Upright posts. C--Transverse beams. D--Head of the stamp.

E--Its tooth. F--The hole in the stamp-stem. G--Iron bar. H--Masses of

lead. I--The bronze saddle. K--Axle. L--Its arms. M--Little iron axle.

N--Bronze pipe.]

The cakes of copper, put into wheelbarrows, are carried into the third

part of the building, where each is laid upon a saddle, and is broken up

by the impact of successive blows from the iron-shod stamp. This machine

is made by placing upon the ground a block of oak, five feet long and

three feet wide and thick; it is cut out in the middle for a length of

two feet and two palms, a width of two feet, and a depth of three palms

and two digits, and is open in front; the higher part of it is at the

back, and the wide part lies flat in the block. In the middle of it is

placed a bronze saddle. Its base is a palm and two digits wide, and is

planted between two masses of lead, and extends under them to a depth of

a palm on both sides. The whole saddle is three palms and two digits

wide, a foot long, and two palms thick. Upon each end of the block

stands a post, a cubit wide and thick, the upper end of which is

somewhat cut away and is mortised into the beams of the building. At a

height of four feet and two digits above the block there are joined to

the posts two transverse beams, each of which is three palms wide and

thick; their ends are mortised into the upright posts, and holes are

bored through them; in the holes are driven iron claves, horned in front

and so driven into the post that one of the horns of each points upward

and the other downward; the other end of each clavis is perforated, and

a wide iron wedge is inserted and driven into the holes, and thus holds

the transverse beams in place. These transverse beams have in the middle

a square opening three palms and half a digit wide in each direction,

through which the iron-shod stamp passes. At a height of three feet and

two palms above these transverse beams there are again two beams of the

same kind, having also a square opening and holding the same stamp. This

stamp is square, eleven feet long, three palms wide and thick; its iron

shoe is a foot and a palm long; its head is two palms long and wide, a

palm two digits thick at the top, and at the bottom the same number of

digits, for it gradually narrows. But the tail is three palms long;

where the head begins is two palms wide and thick, and the further it

departs from the same the narrower it becomes. The upper part is

enclosed in the stamp-stem, and it is perforated so that an iron bolt

may be driven into it; it is bound by three rectangular iron bands, the

lowest of which, a palm wide, is between the iron shoe and the head of

the stamp; the middle band, three digits wide, follows next and binds

round the head of the stamp, and two digits above is the upper one,

which is the same number of digits wide. At a distance of two feet and

as many digits above the lowest part of the iron shoe, is a rectangular

tooth, projecting from the stamp for a distance of a foot and a palm; it

is two palms thick, and when it has extended to a distance of six digits

from the stamp it is made two digits narrower. At a height of three

palms upward from the tooth there is a round hole in the middle of the

stamp-stem, into which can be thrust a round iron bar two feet long and

a digit and a half in diameter; in its hollow end is fixed a wooden

handle two palms and the same number of digits long. The bar rests on

the lower transverse beam, and holds up the stamp when it is not in use.

The axle which raises the stamp has on each side two arms, which are two

palms and three digits distant from each other, and which project from

the axle a foot, a palm and two digits; penetrating through them are

bolts, driven in firmly; the arms are each a palm and two digits wide

and thick, and their round heads, for a foot downward on either side,

are covered with iron plates of the same width as the arms and fastened

by iron nails. The head of each arm has a round hole, into which is

inserted an iron pin, passing through a bronze pipe; this little axle

has at the one end a wide head, and at the other end a perforation

through which is driven an iron nail, lest this little axle should fall

out of the arms. The bronze pipe is two palms long and one in diameter;

the little iron axle penetrates through its round interior, which is two

digits in diameter. The bronze pipe not only revolves round the little

iron axle, but it also rotates with it; therefore, when the axle

revolves, the little axle and the bronze tube in their turn raise the

tooth and the stamp. When the little iron axle and the bronze pipe have

been taken out of the arms, the tooth of the stamps is not raised, and

other stamps may be raised without this one. Further on, a drum with

spindles fixed around the axle of a water-wheel moves the axle of a

toothed drum, which depresses the sweeps of the bellows in the adjacent

fourth part of the building; but it turns in the contrary direction; for

the axis of the drum which raises the stamps turns toward the north,

while that one which depresses the sweeps of the bellows turns toward

the south.

[Illustration 504 (Hearths for heating copper cakes): A--Back wall.

B--Walls at the sides. C--Upright posts. D--Chimney. E--The cakes

arranged. F--Iron plates. G--Rocks. H--Rabble with two prongs.

I--Hammers.]

Those cakes which are too thick to be rapidly broken by blows from the

iron-shod stamp, such as are generally those which have settled in the

bottom of the crucible,[9] are carried into the first part of the

building. They are there heated in a furnace, which is twenty-eight feet

distant from the second long wall and twelve feet from the second

transverse wall. The three sides of this furnace are built of

rectangular rocks, upon which bricks are laid; the back furnace wall is

three feet and a palm high, and the rear of the side walls is the same;

the side walls are sloping, and where the furnace is open in front they

are only two feet and three palms high; all the walls are a foot and a

palm thick. Upon these walls stand upright posts not less thick, in

order that they may bear the heavy weight placed upon them, and they are

covered with lute; these posts support the sloping chimney and penetrate

through the roof. Moreover, not only the ribs of the chimney, but also

the rafters, are covered thickly with lute. The hearth of the furnace is

six feet long on each side, is sloping, and is paved with bricks. The

cakes of copper are placed in the furnace and heated in the following

way. They are first of all placed in the furnace in rows, with as many

small stones the size of an egg between, so that the heat of the fire

can penetrate through the spaces between them; indeed, those cakes which

are placed at the bottom of the crucible are each raised upon half a

brick for the same reason. But lest the last row, which lies against the

mouth of the furnace, should fall out, against the mouth are placed iron

plates, or the copper cakes which are the first taken from the crucible

when copper is made, and against them are laid exhausted liquation cakes

or rocks. Then charcoal is thrown on the cakes, and then live coals; at

first the cakes are heated by a gentle fire, and afterward more charcoal

is added to them until it is at times three-quarters of a foot deep. A

fiercer fire is certainly required to heat the hard cakes of copper than

the fragile ones. When the cakes have been sufficiently heated, which

usually occurs within the space of about two hours, the exhausted

liquation cakes or the rocks and the iron plate are removed from the

mouth of the furnace. Then the hot cakes are taken out row after row

with a two-pronged rabble, such as the one which is used by those who

"dry" the exhausted liquation cakes. Then the first cake is laid upon

the exhausted liquation cakes, and beaten by two workmen with hammers

until it breaks; the hotter the cakes are, the sooner they are broken

up; the less hot, the longer it takes, for now and then they bend into

the shape of copper basins. When the first cake has been broken, the

second is put on to the other fragments and beaten until it breaks into

pieces, and the rest of the cakes are broken up in the same manner in

due order. The head of the hammer is three palms long and one wide, and

sharpened at both ends, and its handle is of wood three feet long. When

they have been broken by the stamp, if cold, or with hammers if hot, the

fragments of copper or the cakes are carried into the store-room for

copper.

The foreman of the works, according to the different proportions of

silver in each _centumpondium_ of copper, alloys it with lead, without

which he could not separate the silver from the copper.[10] If there be

a moderate amount of silver in the copper, he alloys it fourfold; for

instance, if in three-quarters of a _centumpondium_ of copper there is

less than the following proportions, _i.e._: half a _libra_ of silver,

or half a _libra_ and a _sicilicus_, or half a _libra_ and a

_semi-uncia_, or half a _libra_ and _semi-uncia_ and a _sicilicus_, then

rich lead--that is, that from which the silver has not yet been

separated--is added, to the amount of half a _centumpondium_ or a whole

_centumpondium_, or a whole and a half, in such a way that there may be

in the copper-lead alloy some one of the proportions of silver which I

have just mentioned, which is the first alloy. To this "first" alloy is

added such a weight of de-silverized lead or litharge as is required to

make out of all of these a single liquation cake that will contain

approximately two _centumpondia_ of lead; but as usually from one

hundred and thirty _librae_ of litharge only one hundred _librae_ of

lead are made, a greater proportion of litharge than of de-silverized

lead is added as a supplement. Since four cakes of this kind are placed

at the same time into the furnace in which the silver and lead is

liquated from copper, there will be in all the cakes three

_centumpondia_ of copper and eight _centumpondia_ of lead. When the lead

has been liquated from the copper, it weighs six _centumpondia_, in each

_centumpondium_ of which there is a quarter of a _libra_ and almost a

_sicilicus_ of silver. Only seven _unciae_ of the silver remain in the

exhausted liquation cakes and in that copper-lead alloy which we call

"liquation thorns"; they are not called by this name so much because

they have sharp points as because they are base. If in three-quarters of

a _centumpondium_ of copper there are less than seven _uncia_ and a

_semi-uncia_ or a _bes_ of silver, then so much rich lead must be added

as to make in the copper and lead alloy one of the proportions of silver

which I have already mentioned. This is the "second" alloy. To this is

again to be added as great a weight of de-silverized lead, or of

litharge, as will make it possible to obtain from that alloy a liquation

cake containing two and a quarter _centumpondia_ of lead, in which

manner in four of these cakes there will be three _centumpondia_ of

copper and nine _centumpondia_ of lead. The lead which liquates from

these cakes weighs seven _centumpondia_, in each _centumpondium_ of

which there is a quarter of a _libra_ of silver and a little more than a

_sicilicus_. About seven _unciae_ of silver remain in the exhausted

liquation cakes and in the liquation thorns, if we may be allowed to

make common the old name (_spinae_ = thorns) and bestow it upon a new

substance. If in three-quarters of a _centumpondium_ of copper there is

less than three-quarters of a _libra_ of silver, or three-quarters and a

_semi-uncia_, then as much rich lead must be added as will produce one

of the proportions of silver in the copper-lead alloy above mentioned;

this is the "third" alloy. To this is added such an amount of

de-silverized lead or of litharge, that a liquation cake made from it

contains in all two and three-quarters _centumpondia_ of lead. In this

manner four such cakes will contain three _centumpondia_ of copper and

eleven _centumpondia_ of lead. The lead which these cakes liquate, when

they are melted in the furnace, weighs about nine _centumpondia_, in

each _centumpondium_ of which there is a quarter of a _libra_ and more

than a _sicilicus_ of silver; and seven _unciae_ of silver remain in the

exhausted liquation cakes and in the liquation thorns. If, however, in

three-quarters of a _centumpondium_ of copper there is less than

ten-twelfths of a _libra_ or ten-twelfths of a _libra_ and a

_semi-uncia_ of silver, then such a proportion of rich lead is added as

will produce in the copper-lead alloy one of the proportions of silver

which I mentioned above; this is the "fourth" alloy. To this is added

such a weight of de-silverized lead or of litharge, that a liquation

cake made from it contains three _centumpondia_ of lead, and in four

cakes of this kind there are three _centumpondia_ of copper and twelve

_centumpondia_ of lead. The lead which is liquated therefrom weighs

about ten _centumpondia_, in each _centumpondium_ of which there is a

quarter of a _libra_ and more than a _semi-uncia_ of silver, or seven

_unciae_; a _bes_, or seven _unciae_ and a _semi-uncia_, of silver

remain in the exhausted liquation cakes and in the liquation thorns.

[Illustration 508 (Blast Furnaces): A--Furnace in which "slags" are

re-smelted. B--Furnace in which copper is alloyed with lead. C--Door.

D--Forehearths on the ground. E--Copper moulds. F--Rabble. G--Hook.

H--Cleft stick. I--Arm of the crane. K--The hook of its chain.]

Against the second long wall in the second part of the building, whose

area is eighty feet long by thirty-nine feet wide, are four furnaces in

which the copper is alloyed with lead, and six furnaces in which "slags"

are re-smelted. The interior of the first kind of furnace is a foot and

three palms wide, two feet three digits long; and of the second is a

foot and a palm wide and a foot three palms and a digit long. The side

walls of these furnaces are the same height as the furnaces in which

gold or silver ores are smelted. As the whole room is divided into two

parts by upright posts, the front part must have, first, two furnaces in

which "slags" are re-melted; second, two furnaces in which copper is

alloyed with lead; and third, one furnace in which "slags" are

re-melted. The back part of the room has first, one furnace in which

"slags" are re-melted; next, two furnaces in which copper is alloyed

with lead; and third, two furnaces in which "slags" are re-melted. Each

of these is six feet distant from the next; on the right side of the

first is a space of three feet and two palms, and on the left side of

the last one of seven feet. Each pair of furnaces has a common door, six

feet high and a cubit wide, but the first and the tenth furnace each has

one of its own. Each of the furnaces is set in an arch of its own in the

back wall, and in front has a forehearth pit; this is filled with a

powder compound rammed down and compressed in order to make a crucible.

Under each furnace is a hidden receptacle for the moisture,[11] from

which a vent is made through the back wall toward the right, which

allows the vapour to escape. Finally, to the right, in front, is the

copper mould into which the copper-lead alloy is poured from the

forehearth, in order that liquation cakes of equal weight may be made.

This copper mould is a digit thick, its interior is two feet in diameter

and six digits deep. Behind the second long wall are ten pairs of

bellows, two machines for compressing them, and twenty instruments for

inflating them. The way in which these should be made may be understood

from Book IX.

The smelter, when he alloys copper with lead, with his hand throws into

the heated furnace, first the large fragments of copper, then a

basketful of charcoal, then the smaller fragments of copper. When the

copper is melted and begins to run out of the tap-hole into the

forehearth, he throws litharge into the furnace, and, lest part of it

should fly away, he first throws charcoal over it, and lastly lead. As

soon as he has thrown into the furnace the copper and the lead, from

which alloy the first liquation cake is made, he again throws in a

basket of charcoal, and then fragments of copper are thrown over them,

from which the second cake may be made. Afterward with a rabble he skims

the "slag" from the copper and lead as they flow into the forehearth.

Such a rabble is a board into which an iron bar is fixed; the board is

made of elder-wood or willow, and is ten digits long, six wide, and one

and a half digits thick; the iron bar is three feet long, and the wooden

handle inserted into it is two and a half feet long. While he purges the

alloy and pours it out with a ladle into the copper mould, the fragments

of copper from which he is to make the second cake are melting. As soon

as this begins to run down he again throws in litharge, and when he has

put on more charcoal he adds the lead. This operation he repeats until

thirty liquation cakes have been made, on which work he expends nine

hours, or at most ten; if more than thirty cakes must be made, then he

is paid for another shift when he has made an extra thirty.

At the same time that he pours the copper-lead alloy into the copper

mould, he also pours water slowly into the top of the mould. Then, with

a cleft stick, he takes a hook and puts its straight stem into the

molten cake. The hook itself is a digit and a half thick; its straight

stem is two palms long and two digits wide and thick. Afterward he pours

more water over the cakes. When they are cold he places an iron ring in

the hook of the chain let down from the pulley of the crane arm; the

inside diameter of this ring is six digits, and it is about a digit and

a half thick; the ring is then engaged in the hook whose straight stem

is in the cake, and thus the cake is raised from the mould and put into

its place.

The copper and lead, when thus melted, yield a small amount of

"slag"[12] and much litharge. The litharge does not cohere, but falls to

pieces like the residues from malt from which beer is made. _Pompholyx_

adheres to the walls in white ashes, and to the sides of the furnace

adheres _spodos_.

In this practical manner lead is alloyed with copper in which there is

but a moderate portion of silver. If, however, there is much silver in

it, as, for instance, two _librae_, or two _librae_ and a _bes_, to the

_centumpondium_,--which weighs one hundred and thirty-three and a third

_librae_, or one hundred and forty-six _librae_ and a _bes_,[13]--then

the foreman of the works adds to a _centumpondium_ of such copper three

_centumpondia_ of lead, in each _centumpondium_ of which there is a

third of a _libra_ of silver, or a third of a _libra_ and a

_semi-uncia_. In this manner three liquation cakes are made, which

contain altogether three _centumpondia_ of copper and nine

_centumpondia_ of lead.[14] The lead, when it has been liquated from the

copper, weighs seven _centumpondia_; and in each _centumpondium_--if the

_centumpondium_ of copper contain two _librae_ of silver, and the lead

contain a third of a _libra_--there will be a _libra_ and a sixth and

more than a _semi-uncia_ of silver; while in the exhausted liquation

cakes, and in the liquation thorns, there remains a third of a _libra_.

If a _centumpondium_ of copper contains two _librae_ and a _bes_ of

silver, and the lead a third of a _libra_ and a _semi-uncia_, there will

be in each liquation cake one and a half _librae_ and a _semi-uncia_,

and a little more than a _sicilicus_ of silver. In the exhausted

liquation cakes there remain a third of a _libra_ and a _semi-uncia_ of

silver.

[Illustration 510 (Furnaces enriching copper bottoms): A--Furnace.

B--Forehearth. C--Dipping-Pot. D--Cakes.]

If there be in the copper only a minute proportion of silver, it cannot

be separated easily until it has been re-melted in other furnaces, so

that in the "bottoms" there remains more silver and in the "tops"

less.[15] This furnace, vaulted with unbaked bricks, is similar to an

oven, and also to the cupellation furnace, in which the lead is

separated from silver, which I described in the last book. The crucible

is made of ashes, in the same manner as in the latter, and in the front

of the furnace, three feet above the floor of the building, is the mouth

out of which the re-melted copper flows into a forehearth and a

dipping-pot. On the left side of the mouth is an aperture, through which

beech-wood may be put into the furnace to feed the fire. If in a

_centumpondium_ of copper there were a sixth of a _libra_ and a

_semi-uncia_ of silver, or a quarter of a _libra_, or a quarter of a

_libra_ and a _semi-uncia_--there is re-melted at the same time

thirty-eight _centumpondia_ of it in this furnace, until there remain in

each _centumpondium_ of the copper "bottoms" a third of a _libra_ and a

_semi-uncia_ of silver. For example, if in each _centumpondium_ of

copper not yet re-melted, there is a quarter of a _libra_ and a

_semi-uncia_ of silver, then the thirty-eight _centumpondia_ that are

smelted together must contain a total of eleven _librae_ and an _uncia_

of silver. Since from fifteen _centumpondia_ of re-melted copper there

was a total of four and a third _librae_ and a _semi-uncia_ of silver,

there remain only two and a third _librae_. Thus there is left in the

"bottoms," weighing twenty-three _centumpondia_, a total of eight and

three-quarter _librae_ of silver. Therefore, each _centumpondium_ of

this contains a third of a _libra_ and a _semi-uncia_, a _drachma_, and

the twenty-third part of a _drachma_ of silver; from such copper it is

profitable to separate the silver. In order that the master may be more

certain of the number of _centumpondia_ of copper in the "bottoms," he

weighs the "tops" that have been drawn off from it; the "tops" were

first drawn off into the dipping-pot, and cakes were made from them.

Fourteen hours are expended on the work of thus dividing the copper. The

"bottoms," when a certain weight of lead has been added to them, of

which alloy I shall soon speak, are melted in the blast furnace;

liquation cakes are then made, and the silver is afterward separated

from the copper. The "tops" are subsequently melted in the blast

furnace, and re-melted in the refining furnace, in order that red copper

shall be made[16]; and the "tops" from this are again smelted in the

blast furnace, and then again in the refining furnace, that therefrom

shall be made _caldarium_ copper. But when the copper, yellow or red or

_caldarium_ is re-smelted in the refining furnace, forty _centumpondia_

are placed in it, and from it they make at least twenty, and at most

thirty-five, _centumpondia_. About twenty-two _centumpondia_ of

exhausted liquation cakes and ten of yellow copper and eight of red, are

simultaneously placed in this latter furnace and smelted, in order that

they may be made into refined copper.

The copper "bottoms" are alloyed in three different ways with lead.[17]

First, five-eighths of a _centumpondium_ of copper and two and

three-quarters _centumpondia_ of lead are taken; and since one liquation

cake is made from this, therefore two and a half _centumpondia_ of

copper and eleven _centumpondia_ of lead make four liquation cakes.

Inasmuch as in each _centumpondium_ of copper there is a third of a

_libra_ of silver, there would be in the whole of the copper

ten-twelfths of a _libra_ of silver; to these are added four

_centumpondia_ of lead re-melted from "slags," each _centumpondium_ of

which contains a _sicilicus_ and a _drachma_ of silver, which weights

make up a total of an _uncia_ and a half of silver. There is also added

seven _centumpondia_ of de-silverized lead, in each _centumpondium_ of

which there is a _drachma_ of silver; therefore in the four cakes of

copper-lead alloy there is a total of a _libra_, a _sicilicus_ and a

_drachma_ of silver. In each single _centumpondium_ of lead, after it

has been liquated from the copper, there is an _uncia_ and a _drachma_

of silver, which alloy we call "poor" argentiferous lead, because it

contains but little silver. But as five cakes of that kind are placed

together in the furnace, they liquate from them usually as much as nine

and three-quarters _centumpondia_ of poor argentiferous lead, in each

_centumpondium_ of which there is an _uncia_ and a _drachma_ of silver,

or a total of ten _unciae_ less four _drachmae_. Of the liquation thorns

there remain three _centumpondia_, in each _centumpondium_ of which

there are three _sicilici_ of silver; and there remain four

_centumpondia_ of exhausted liquation cakes, each _centumpondium_ of

which contains a _semi-uncia_ or four and a half _drachmae_. Inasmuch as

in a _centumpondium_ of copper "bottoms" there is a third of a _libra_

and a _semi-uncia_ of silver, in five of those cakes there must be more

than one and a half _unciae_ and half a _drachma_ of silver.

Then, again, from another two and a half _centumpondia_ of copper

"bottoms," together with eleven _centumpondia_ of lead, four liquation

cakes are made. If in each _centumpondium_ of copper there was a third

of a _libra_ of silver, there would be in the whole of the

_centumpondia_ of base metal five-sixths of a _libra_ of the precious

metal. To this copper is added eight _centumpondia_ of poor

argentiferous lead, each _centumpondium_ of which contains an _uncia_

and a _drachma_ of silver, or a total of three-quarters of a _libra_ of

silver. There is also added three _centumpondia_ of de-silverized lead,

in each _centumpondium_ of which there is a _drachma_ of silver.

Therefore, four liquation cakes contain a total of a _libra_, seven

_unciae_, a _sicilicus_ and a _drachma_ of silver; thus each

_centumpondium_ of lead, when it has been liquated from the copper,

contains an _uncia_ and a half and a _sicilicus_ of silver, which alloy

we call "medium" silver-lead.

Then, again, from another two and a half _centumpondia_ of copper

"bottoms," together with eleven _centumpondia_ of lead, they make four

liquation cakes. If in each _centumpondium_ of copper there were

likewise a third of a _libra_ of silver, there will be in all the weight

of the base metal five-sixths of a _libra_ of the precious metal. To

this is added nine _centumpondia_ of medium silver-lead, each

_centumpondium_ of which contains an _uncia_ and a half and a

_sicilicus_ of silver; or a total of a _libra_ and a quarter and a

_semi-uncia_ and a _sicilicus_ of silver. And likewise they add two

_centumpondia_ of poor silver-lead, in each of which there is an _uncia_

and a _drachma_ of silver. Therefore the four liquation cakes contain

two and a third _librae_ of silver. Each _centumpondium_ of lead, when

it has been liquated from the copper, contains a sixth of a _libra_ and

a _semi-uncia_ and a _drachma_ of silver. This alloy we call "rich"

silver-lead; it is carried to the cupellation furnace, in which lead is

separated from silver. I have now mentioned in how many ways copper

containing various proportions of silver is alloyed with lead, and how

they are melted together in the furnace and run into the casting pan.

[Illustration 514 (Crane for liquation cakes): A--Crane. B--Drum

consisting of rundles. C--Toothed drum. D--Trolley and its wheels.

E--Triangular board. F--Cakes. G--Chain of the crane. H--Its hook.

I--Ring. K--The tongs.]

Now I will speak of the method by which lead is liquated from copper

simultaneously with the silver. The liquation cakes are raised from the

ground with the crane, and placed on the copper plates of the furnaces.

The hook of the chain let down from the arm of the crane, is inserted in

a ring of the tongs, one jaw of which has a tooth; a ring is engaged in

each of the handles of the tongs, and these two rings are engaged in a

third, in which the hook of the chain is inserted. The tooth on the one

jaw of the tongs is struck by a hammer, and driven into the hole in the

cake, at the point where the straight end of the hook was driven into

it when it was lifted out of the copper mould; the other jaw of the

tongs, which has no tooth, squeezes the cake, lest the tooth should fall

out of it; the tongs are one and a half feet long, each ring is a digit

and a half thick, and the inside is a palm and two digits in diameter.

Those cranes by which the cakes are lifted out of the copper pans and

placed on the ground, and lifted up again from there and placed in the

furnaces, are two in number--one in the middle space between the third

transverse wall and the two upright posts, and the other in the middle

space between the same posts and the seventh transverse wall. The

rectangular crane-post of both of these is two feet wide and thick, and

is eighteen feet from the third long wall, and nineteen from the second

long wall. There are two drums in the framework of each--one drum

consisting of rundles, the other being toothed. The crane-arm of each

extends seventeen feet, three palms and as many digits from the post.

The trolley of each crane is two feet and as many palms long, a foot and

two digits wide, and a palm and two digits thick; but where it runs

between the beams of the crane-arm it is three digits wide and a palm

thick; it has five notches, in which turn five brass wheels, four of

which are small, and the fifth much larger than the rest. The notches in

which the small wheels turn are two palms long and as much as a palm

wide; those wheels are a palm wide and a palm and two digits in

diameter; four of the notches are near the four corners of the trolley;

the fifth notch is between the two front ones, and it is two palms back

from the front. Its pulley is larger than the rest, and turns in its own

notch; it is three palms in diameter and one palm wide, and grooved on

the circumference, so that the iron chain may run in the groove. The

trolley has two small axles, to the one in front are fastened three, and

to the one at the back, the two wheels; two wheels run on the one beam

of the crane-arm, and two on the other; the fifth wheel, which is larger

than the others, runs between those two beams. Those people who have no

cranes place the cakes on a triangular board, to which iron cleats are

affixed, so that it will last longer; the board has three iron chains,

which are fixed in an iron ring at the top; two workmen pass a pole

through the ring and carry it on their shoulders, and thus take the cake

to the furnace in which silver is separated from copper.

From the vicinity of the furnaces in which copper is mixed with lead and

the "slags" are re-melted, to the third long wall, are likewise ten

furnaces, in which silver mixed with lead is separated from copper. If

this space is eighty feet and two palms long, and the third long wall

has in the centre a door three feet and two palms wide, then the spaces

remaining at either side of the door will be thirty-eight feet and two

palms; and if each of the furnaces occupies four feet and a palm, then

the interval between each furnace and the next one must be a foot and

three palms; thus the width of the five furnaces and four interspaces

will be twenty-eight feet and a palm. Therefore, there remain ten feet

and a palm, which measurement is so divided that there are five feet and

two digits between the first furnace and the transverse wall, and as

many feet and digits between the fifth furnace and the door; similarly

in the other part of the space from the door to the sixth furnace, there

must be five feet and two digits, and from the tenth furnace to the

seventh transverse wall, likewise, five feet and two digits. The door is

six feet and two palms high; through it the foreman of the _officina_

and the workmen enter the store-room in which the silver-lead alloy is

kept.

[Illustration 517 (Liquation Furnace): A--Sole-stones. B--Rectangular

stones. C--Copper plates. D--Front panel. E--Side panels. F--Bar.

G--Front end of the long iron rods. H--Short chain. I--Hooked rod.

K--Wall which protects the third long wall from injury by fire. L--Third

long wall. M--Feet of the panels. N--Iron blocks. O--Cakes. P--Hearth.

Q--Receiving-pit.]

Each furnace has a bed, a hearth, a rear wall, two sides and a front,

and a receiving-pit. The bed consists of two sole-stones, four

rectangular stones, and two copper plates; the sole-stones are five feet

and a palm long, a cubit wide, a foot and a palm thick, and they are

sunk into the ground, so that they emerge a palm and two digits; they

are distant from each other about three palms, yet the distance is

narrower at the back than the front. Each of the rectangular stones is

two feet and as many palms long, a cubit wide, and a cubit thick at the

outer edge, and a foot and a palm thick on the inner edge which faces

the hearth, thus they form an incline, so that there is a slope to the

copper plates which are laid upon them. Two of these rectangular stones

are placed on one sole-stone; a hole is cut in the upper edge of each,

and into the holes are placed iron clamps, and lead is poured in; they

are so placed on the sole-stones that they project a palm at the sides,

and at the front the sole-stones project to the same extent; if

rectangular stones are not available, bricks are laid in their place.

The copper plates are four feet two palms and as many digits long, a

cubit wide, and a palm thick; each edge has a protuberance, one at the

front end, the other at the back; these are a palm and three digits

long, and a palm wide and thick. The plates are so laid upon the

rectangular stones that their rear ends are three digits from the third

long wall; the stones project beyond the plate the same number of digits

in front, and a palm and three digits at the sides. When the plates have

been joined, the groove which is between the protuberances is a palm and

three digits wide, and four feet long, and through it flows the

silver-lead which liquates from the cakes. When the plates are corroded

either by the fire or by the silver-lead, which often adheres to them in

the form of stalactites, and is chipped off, they are exchanged, the

right one being placed to the left, and the left one, on the contrary,

to the right; but the left side of the plates, which, when the fusion of

the copper took place, came into contact with the copper, must lie flat;

so that when the exchange of the plates has been carried out, the

protuberances, which are thus on the underside, raise the plate from the

stones, and they have to be partially chipped off, lest they should

prove an impediment to the work; and in each of their places is laid a

piece of iron, three palms long, a digit thick at both ends, and a palm

thick in the centre for the length of a palm and three digits.

The passage under the plates between the rectangular stones is a foot

wide at the back, and a foot and a palm wide at the front, for it

gradually widens out. The hearth, which is between the sole-stones, is

covered with a bed of hearth-lead, taken from the crucible in which lead

is separated from silver. The rear end is the highest, and should be so

high that it reaches to within six digits of the plates, from which

point it slopes down evenly to the front end, so that the argentiferous

lead alloy which liquates from the cakes can flow into the

receiving-pit. The wall built against the third long wall in order to

protect it from injury by fire, is constructed of bricks joined together

with lute, and stands on the copper plates; this wall is two feet, a

palm and two digits high, two palms thick, and three feet, a palm and

three digits wide at the bottom, for it reaches across both of them; at

the top it is three feet wide, for it rises up obliquely on each side.

At each side of this wall, at a height of a palm and two digits above

the top of it, there is inserted in a hole in the third long wall a

hooked iron rod, fastened in with molten lead; the rod projects two

palms from the wall, and is two digits wide and one digit thick; it has

two hooks, the one at the side, the other at the end. Both of these

hooks open toward the wall, and both are a digit thick, and both are

inserted in the last, or the adjacent, links of a short iron chain. This

chain consists of four links, each of which is a palm and a digit long

and half a digit thick; the first link is engaged in the first hole in a

long iron rod, and one or other of the remaining three links engages the

hook of the hooked rod. The two long rods are three feet and as many

palms and digits long, two digits wide, and one digit thick; both ends

of both of these rods have holes, the back one of which is round and a

digit in diameter, and in this is engaged the first link of the chain as

I have stated; the hole at the front end is two digits and a half long

and a digit and a half wide. This end of each rod is made three digits

wide, while for the rest of its length it is only two digits, and at the

back it is two and a half digits. Into the front hole of each rod is

driven an iron bar, which is three feet and two palms long, two digits

wide and one thick; in the end of this bar are five small square holes,

two-thirds of a digit square; each hole is distant from the other half a

digit, the first being at a distance of about a digit from the end. Into

one of these holes the refiner drives an iron pin; if he should desire

to make the furnace narrower, then he drives it into the last hole; if

he should desire to widen it, then into the first hole; if he should

desire to contract it moderately, then into one of the middle holes. For

the same reason, therefore, the hook is sometimes inserted into the last

link of the chain, and sometimes into the third or the second. The

furnace is widened when many cakes are put into it, and contracted when

there are but few, but to put in more than five is neither usual nor

possible; indeed, it is because of thin cakes that the walls are

contracted. The bar has a hump, which projects a digit on each side at

the back, of the same width and thickness as itself. These humps

project, lest the bar should slip through the hole of the right-hand

rod, in which it remains fixed when it, together with the rods, is not

pressing upon the furnace walls.

[Illustration 519 (Liquation Furnaces): A--Furnace in which the

operation of liquation is being performed. B--Furnace in which it is not

being performed. C--Receiving-pit. D--Moulds. E--Cakes. F--Liquation

thorns.]

There are three panels to the furnace--two at the sides, one in front

and another at the back. Those which are at the sides are three feet and

as many palms and two digits long, and two feet high; the front one is

two feet and a palm and three digits long, and, like the side ones, two

feet high. Each consists of iron bars, of feet, and of iron plates.

Those which are at the side have seven bars, the lower and upper of

which are of the same length as the panels; the former holds up the

upright bars; the latter is placed upon them; the uprights are five in

number, and have the same height as the panels; the middle ones are

inserted into holes in the upper and lower bars; the outer ones are made

of one and the same bar as the lower and upper ones. They are two digits

wide and one thick. The front panel has five bars; the lower one holds

similar uprights, but there are three of them only; the upper bar is

placed on them. Each of these panels has two feet fixed at each end of

the lower bar, and these are two palms long, one wide, and a digit

thick. The iron plates are fastened to the inner side of the bars with

iron wire, and they are covered with lute, so that they may last longer

and may be uninjured by the fire. There are, besides, iron blocks three

palms long, one wide, and a digit and a half thick; the upper surface of

these is somewhat hollowed out, so that the cakes may stand in them;

these iron blocks are dipped into a vessel in which there is clay mixed

with water, and they are used only for placing under the cakes of copper

and lead alloy made in the furnaces. There is more silver in these than

in those which are made of liquation thorns, or furnace accretions, or

re-melted "slags." Two iron blocks are placed under each cake, in order

that, by raising it up, the fire may bring more force to bear upon it;

the one is put on the right bed-plate, the other on the left. Finally,

outside the hearth is the receiving-pit, which is a foot wide and three

palms deep; when this is worn away it is restored with lute alone, which

easily retains the lead alloy.

If four liquation cakes are placed on the plates of each furnace, then

the iron blocks are laid under them; but if the cakes are made from

copper "bottoms," or from liquation thorns, or from the accretions or

"slags," of which I have partly written above and will further describe

a little later, there are five of them, and because they are not so

large and heavy, no blocks are placed under them. Pieces of charcoal six

digits long are laid between the cakes, lest they should fall one

against the other, or lest the last one should fall against the wall

which protects the third long wall from injury by fire. In the middle

empty spaces, long and large pieces of charcoal are likewise laid. Then

when the panels have been set up, and the bar has been closed, the

furnace is filled with small charcoal, and a wicker basket full of

charcoal is thrown into the receiving-pit, and over that are thrown live

coals; soon afterward the burning coal, lifted up in a shovel, is spread

over all parts of the furnace, so that the charcoal in it may be

kindled; any charcoal which remains in the receiving-pit is thrown into

the passage, so that it may likewise be heated. If this has not been

done, the silver-lead alloy liquated from the cakes is frozen by the

coldness of the passage, and does not run down into the receiving-pit.

After a quarter of an hour the cakes begin to drip silver-lead

alloy,[18] which runs down through the openings between the copper

plates into the passage. When the long pieces of charcoal have burned

up, if the cakes lean toward the wall, they are placed upright again

with a hooked bar, but if they lean toward the front bar they are

propped up by charcoal; moreover, if some cakes shrink more than the

rest, charcoal is added to the former and not to the others. The silver

drips together with the lead, for both melt more rapidly than copper.

The liquation thorns do not flow away, but remain in the passage, and

should be turned over frequently with a hooked bar, in order that the

silver-lead may liquate away from them and flow down into the receiving

pit; that which remains is again melted in the blast furnace, while that

which flows into the receiving pit is at once carried with the remaining

products to the cupellation furnace, where the lead is separated from

the silver. The hooked bar has an iron handle two feet long, in which is

set a wooden one four feet long. The silver-lead which runs out into the

receiving-pit is poured out by the refiner with a bronze ladle into

eight copper moulds, which are two palms and three digits in diameter;

these are first smeared with a lute wash so that the cakes of

silver-lead may more easily fall out when they are turned over. If the

supply of moulds fails because the silver-lead flows down too rapidly

into the receiving-pit, then water is poured on them, in order that the

cakes may cool and be taken out of them more rapidly; thus the same

moulds may be used again immediately; if no such necessity urges the

refiner, he washes over the empty moulds with a lute wash. The ladle is

exactly similar to that which is used in pouring out the metals that are

melted in the blast furnace. When all the silver-lead has run down from

the passage into the receiving-pit, and has been poured out into copper

moulds, the thorns are drawn out of the passage into the receiving-pit

with a rabble; afterward they are raked on to the ground from the

receiving-pit, thrown with a shovel into a wheelbarrow, and, having been

conveyed away to a heap, are melted once again. The blade of the rabble

is two palms and as many digits long, two palms and a digit wide, and

joined to its back is an iron handle three feet long; into the iron

handle is inserted a wooden one as many feet in length.

The residue cakes, after the silver-lead has been liquated from the

copper, are called "exhausted liquation cakes" (_fathiscentes_), because

when thus smelted they appear to be dried up. By placing a crowbar under

the cakes they are raised up, seized with tongs, and placed in the

wheelbarrow; they are then conveyed away to the furnace in which they

are "dried." The crowbar is somewhat similar to those generally used to

chip off the accretions that adhere to the walls of the blast furnace.

The tongs are two and a half feet long. With the same crowbar the

stalactites are chipped off from the copper plates from which they hang,

and with the same instrument the iron blocks are struck off the

exhausted liquation cakes to which they adhere. The refiner has

performed his day's task when he has liquated the silver-lead from

sixteen of the large cakes and twenty of the smaller ones; if he

liquates more than this, he is paid separately for it at the price for

extraordinary work.

Silver, or lead mixed with silver, which we call _stannum_, is separated

by the above method from copper. This silver-lead is carried to the

cupellation furnace, in which lead is separated from silver; of these

methods I will mention only one, because in the previous book I have

explained them in detail. Amongst us some years ago only forty-four

_centumpondia_ of silver-lead and one of copper were melted together in

the cupellation furnaces, but now they melt forty-six _centumpondia_ of

silver-lead and one and a half _centumpondia_ of copper; in other

places, usually a hundred and twenty _centumpondia_ of silver-lead alloy

and six of copper are melted, in which manner they make about one

hundred and ten _centumpondia_ more or less of litharge and thirty of

hearth-lead. But in all these methods the silver which is in the copper

is mixed with the remainder of silver; the copper itself, equally with

the lead, will be changed partly into litharge and partly into

hearth-lead.[19] The silver-lead alloy which does not melt is taken from

the margin of the crucible with a hooked bar.

[Illustration 522 (Exhausted Liquation Cakes): A--Cakes. B--Hammer.]

The work of "drying" is distributed into four operations, which are

performed in four days. On the first--as likewise on the other three

days--the master begins at the fourth hour of the morning, and with his

assistant chips off the stalactites from the exhausted liquation cakes.

They then carry the cakes to the furnace, and put the stalactites upon

the heap of liquation thorns. The head of the chipping hammer is three

palms and as many digits long; its sharp edge is a palm wide; the round

end is three digits thick; the wooden handle is four feet long.

The master throws pulverised earth into a small vessel, sprinkles water

over it, and mixes it; this he pours over the whole hearth, and

sprinkles charcoal dust over it to the thickness of a digit. If he

should neglect this, the copper, settling in the passages, would adhere

to the copper bed-plates, from which it can be chipped off only with

difficulty; or else it would adhere to the bricks, if the hearth was

covered with them, and when the copper is chipped off these they are

easily broken. On the second day, at the same time, the master arranges

bricks in ten rows; in this manner twelve passages are made. The first

two rows of bricks are between the first and the second openings on the

right of the furnace; the next three rows are between the second and

third openings, the following three rows are between the third and the

fourth openings, and the last two rows between the fourth and fifth

openings. These bricks are a foot and a palm long, two palms and a digit

wide, and a palm and two digits thick; there are seven of these thick

bricks in a row, so there are seventy all together. Then on the first

three rows of bricks they lay exhausted liquation cakes and a layer five

digits thick of large charcoal; then in a similar way more exhausted

liquation cakes are laid upon the other bricks, and charcoal is thrown

upon them; in this manner seventy _centumpondia_ of cakes are put on the

hearth of the furnace. But if half of this weight, or a little more, is

to be "dried," then four rows of bricks will suffice. Those who dry

exhausted liquation cakes[20] made from copper "bottoms" place ninety or

a hundred _centumpondia_[21] into the furnace at the same time. A place

is left in the front part of the furnace for the topmost cakes removed

from the forehearth in which copper is made, these being more suitable

for supporting the exhausted liquation cakes than are iron plates;

indeed, if the former cakes drip copper from the heat, this can be taken

back with the liquation thorns to the first furnace, but melted iron is

of no use to us in these matters. When the cakes of this kind have been

placed in front of the exhausted liquation cakes, the workman inserts

the iron bar into the holes on the inside of the wall, which are at a

height of three palms and two digits above the hearth; the hole to the

left penetrates through into the wall, so that the bar may be pushed

back and forth. This bar is round, eight feet long and two digits in

diameter; on the right side it has a haft made of iron, which is about a

foot from the right end; the aperture in this haft is a palm wide, two

digits high, and a digit thick. The bar holds the exhausted liquation

cakes opposite, lest they should fall down. When the operation of

"drying" is completed, a workman draws out this bar with a crook which

he inserts into the haft, as I will explain hereafter.

[Illustration 525 (Drying Furnace for Liquation): A--Side walls.

B--Front arch. C--Rear arch. D--Wall in the rear arch. E--Inner wall.

F--Vent holes. G--Chimney. H--Hearth. I--Tank. K--Pipe. L--Plug. M--Iron

door. N--Transverse bars. O--Upright bars. P--Plates. Q--Rings of the

bars. R--Chains. S--Rows of bricks. T--Bar. V--Its haft. X--Copper

bed-plates.]

In order that one should understand those things of which I have spoken,

and concerning which I am about to speak, it is necessary for me to give

some information beforehand about the furnace and how it is to be made.

It stands nine feet from the fourth long wall, and as far from the wall

which is between the second and fourth transverse walls. It consists of

walls, an arch, a chimney, an interior wall, and a hearth; the two walls

are at the sides; and they are eleven feet three palms and two digits

long, and where they support the chimney they are eight feet and a palm

high. At the front of the arch they are only seven feet high; they are

two feet three palms and two digits thick, and are made either of rock

or of bricks; the distance between them is eight feet, a palm and two

digits. There are two of the arches, for the space at the rear between

the walls is also arched from the ground, in order that it may be able

to support the chimney; the foundations of these arches are the walls of

the furnace; the span of the arch has the same length as the space

between the walls; the top of the arch is five feet, a palm and two

digits high. In the rear arch there is a wall made of bricks joined with

lime; this wall at a height of a foot and three palms from the ground

has five vent-holes, which are two palms and a digit high, a palm and a

digit wide, of which the first is near the right interior wall, and the

last near the left interior wall, the remaining three in the intervening

space; these vent-holes penetrate through the interior of the wall which

is in the arch. Half-bricks can be placed over the vent-holes, lest too

much air should be drawn into the furnace, and they can be taken out at

times, in order that he who is "drying" the exhausted liquation cakes

may inspect the passages, as they are called, to see whether the cakes

are being properly "dried." The front arch is three feet two palms

distant from the rear one; this arch is the same thickness as that of

the rear arch, but the span is six feet wide; the interior of the arch

itself is of the same height as the walls. A chimney is built upon the

arches and the walls, and is made of bricks joined together with lime;

it is thirty-six feet high and penetrates through the roof. The interior

wall is built against the rear arch and both the side walls, from which

it juts out a foot; it is three feet and the same number of palms high,

three palms thick, and is made of bricks joined together with lute and

smeared thickly with lute, sloping up to the height of a foot above it.

This wall is a kind of shield, for it protects the exterior walls from

the heat of the fire, which is apt to injure them; the latter cannot be

easily re-made, while the former can be repaired with little work.

The hearth is made of lute, and is covered either with copper plates,

such as those of the furnaces in which silver is liquated from copper,

although they have no protuberances, or it may be covered with bricks,

if the owners are unwilling to incur the expense of copper plates. The

wider part of the hearth is made sloping in such a manner that the rear

end reaches as high as the five vent-holes, and the front end of the

hearth is so low that the back of the front arch is four feet, three

palms and as many digits above it, and the front five feet, three palms

and as many digits. The hearth beyond the furnaces is paved with bricks

for a distance of six feet. Near the furnace, against the fourth long

wall, is a tank thirteen feet and a palm long, four feet wide, and a

foot and three palms deep. It is lined on all sides with planks, lest

the earth should fall into it; on one side the water flows in through

pipes, and on the other, if the plug be pulled out, it soaks into the

earth; into this tank of water are thrown the cakes of copper from which

the silver and lead have been separated. The fore part of the front

furnace arch should be partly closed with an iron door; the bottom of

this door is six feet and two digits wide; the upper part is somewhat

rounded, and at the highest point, which is in the middle, it is three

feet and two palms high. It is made of iron bars, with plates fastened

to them with iron wire, there being seven bars--three transverse and

four upright--each of which is two digits wide and half a digit thick.

The lowest transverse bar is six feet and two palms long; the middle one

has the same length; the upper one is curved and higher at the centre,

and thus longer than the other two. The upright bars are two feet

distant from one another; both the outer ones are two feet and as many

palms high; but the centre ones are three feet and two palms. They

project from the upper curved transverse bar and have holes, in which

are inserted the hooks of small chains two feet long; the topmost links

of these chains are engaged in the ring of a third chain, which, when

extended, reaches to one end of a beam which is somewhat cut out. The

chain then turns around the beam, and again hanging down, the hook in

the other end is fastened in one of the links. This beam is eleven feet

long, a palm and two digits wide, a palm thick, and turns on an iron

axle fixed in a nearby timber; the rear end of the beam has an iron pin,

which is three palms and a digit long, and which penetrates through it

where it lies under a timber, and projects from it a palm and two digits

on one side, and three digits on the other side. At this point the pin

is perforated, in order that a ring may be fixed in it and hold it,

lest it should fall out of the beam; that end is hardly a digit thick,

while the other round end is thicker than a digit. When the door is to

be shut, this pin lies under the timber and holds the door so that it

cannot fall; the pin likewise prevents the rectangular iron band which

encircles the end of the beam, and into which is inserted the ring of a

long hook, from falling from the end. The lowest link of an iron chain,

which is six feet long, is inserted in the ring of a staple driven into

the right wall of the furnace, and fixed firmly by filling in with

molten lead. The hook suspended at the top from the ring should be

inserted in one of these lower links, when the door is to be raised;

when the door is to be let down, the hook is taken out of that link and

put into one of the upper links.

[Illustration 527 (Drying Furnace for Liquation): A--The door let down.

B--Bar. C--Exhausted liquation cakes. D--Bricks. E--Tongs.]

On the third day the master sets about the principal operation. First he

throws a basketful of charcoals on to the ground in front of the hearth,

and kindles them by adding live coals, and having thrown live coals on

to the cakes placed within, he spreads them equally all over with an

iron shovel. The blade of the shovel is three palms and a digit long,

and three palms wide; its iron handle is two palms long, and the wooden

one ten feet long, so that it can reach to the rear wall of the furnace.

The exhausted liquation cakes become incandescent in an hour and a half,

if the copper was good and hard, or after two hours, if it was soft and

fragile. The workman adds charcoal to them where he sees it is needed,

throwing it into the furnace through the openings on both sides between

the side walls and the closed door. This opening is a foot and a palm

wide. He lets down the door, and when the "slags" begin to flow he opens

the passages with a bar; this should take place after five hours; the

door is let down over the upper open part of the arch for two feet and

as many digits, so that the master can bear the violence of the heat.

When the cakes shrink, charcoal should not be added to them lest they

should melt. If the cakes made from poor and fragile copper are "dried"

with cakes made from good hard copper, very often the copper so settles

into the passages that a bar thrust into them cannot penetrate them.

This bar is of iron, six feet and two palms long, into which a wooden

handle five feet long is inserted. The refiner draws off the "slags"

with a rabble from the right side of the hearth. The blade of the rabble

is made of an iron plate a foot and a palm wide, gradually narrowing

toward the handle; the blade is two palms high, its iron handle is two

feet long, and the wooden handle set into it is ten feet long.

[Illustration 528 (Drying Furnace for Liquation): A--The door raised.

B--Hooked bar. C--Two-pronged rake. D--Tongs. E--Tank.]

When the exhausted liquation cakes have been "dried," the master raises

the door in the manner I have described, and with a long iron hook

inserted into the haft of the bar he draws it through the hole in the

left wall from the hole in the right wall; afterward he pushes it back

and replaces it. The master then takes out the exhausted liquation cakes

nearest to him with the iron hook; then he pulls out the cakes from the

bricks. This hook is two palms high, as many digits wide, and one thick;

its iron handle is two feet long, and the wooden handle eleven feet

long. There is also a two-pronged rake with which the "dried" cakes are

drawn over to the left side so that they may be seized with tongs; the

prongs of the rake are pointed, and are two palms long, as many digits

wide, and one digit thick; the iron part of the handle is a foot long,

the wooden part nine feet long. The "dried" cakes, taken out of the

hearth by the master and his assistants, are seized with other tongs and

thrown into the rectangular tank, which is almost filled with water.

These tongs are two feet and three palms long, both the handles are

round and more than a digit thick, and the ends are bent for a palm and

two digits; both the jaws are a digit and a half wide in front and

sharpened; at the back they are a digit thick, and then gradually taper,

and when closed, the interior is two palms and as many digits wide.

The "dried" cakes which are dripping copper are not immediately dipped

into the tank, because, if so, they burst in fragments and give out a

sound like thunder. The cakes are afterward taken out of the tank with

the tongs, and laid upon the two transverse planks on which the workmen

stand; the sooner they are taken out the easier it is to chip off the

copper that has become ash-coloured. Finally, the master, with a spade,

raises up the bricks a little from the hearth, while they are still

warm. The blade of the spade is a palm and two digits long, the lower

edge is sharp, and is a palm and a digit wide, the upper end a palm

wide; its handle is round, the iron part being two feet long, and the

wooden part seven and a half feet long.

On the fourth day the master draws out the liquation thorns which have

settled in the passages; they are much richer in silver than those that

are made when the silver-lead is liquated from copper in the liquation

furnace. The "dried" cakes drip but little copper, but nearly all their

remaining silver-lead and the thorns consist of it, for, indeed, in one

_centumpondium_ of "dried" copper there should remain only half an

_uncia_ of silver, and there sometimes remain only three _drachmae_.[22]

Some smelters chip off the metal adhering to the bricks with a hammer,

in order that it may be melted again; others, however, crush the bricks

under the stamps and wash them, and the copper and lead thus collected

is melted again. The master, when he has taken these things away and put

them in their places, has finished his day's work.

[Illustration 530 (Dried Liquation Cakes): A--Tank. B--Board. C--Tongs.

D--"Dried" cakes taken out of the tanks. E--Block. F--Rounded hammer.

G--Pointed hammer.]

The assistants take the "dried" cakes out of the tank on the next day,

place them on an oak block, and first pound them with rounded hammers in

order that the ash-coloured copper may fall away from them, and then

they dig out with pointed picks the holes in the cakes, which contain

the same kind of copper. The head of the round hammer is three palms and

a digit long; one end of the head is round and two digits long and

thick; the other end is chisel-shaped, and is two digits and a half

long. The sharp pointed hammer is the same length as the round hammer,

but one end is pointed, the other end is square, and gradually tapers to

a point.

The nature of copper is such that when it is "dried" it becomes ash

coloured, and since this copper contains silver, it is smelted again in

the blast furnaces.[23]

[Illustration 532 (Copper Refining Furnace): A--Hearth of the furnace.

B--Chimney. C--Common pillar. D--Other pillars. The partition wall is

behind the common pillar and not to be seen. E--Arches. F--Little walls

which protect the partition wall from injury by the fire. G--Crucibles.

H--Second long wall. I--Door. K--Spatula. L--The other spatula. M--The

broom in which is inserted a stick. N--Pestles. O--Wooden mallet.

P--Plate. Q--Stones. R--Iron rod.]

I have described sufficiently the method by which exhausted liquation

cakes are "dried"; now I will speak of the method by which they are made

into copper after they have been "dried." These cakes, in order that

they may recover the appearance of copper which they have to some extent

lost, are melted in four furnaces, which are placed against the second

long wall in the part of the building between the second and third

transverse walls. This space is sixty-three feet and two palms long, and

since each of these furnaces occupies thirteen feet, the space which is

on the right side of the first furnace, and on the left of the fourth,

are each three feet and three palms wide, and the distance between the

second and third furnace is six feet. In the middle of each of these

three spaces is a door, a foot and a half wide and six feet high, and

the middle one is common to the master of each of the furnaces. Each

furnace has its own chimney, which rises between the two long walls

mentioned above, and is supported by two arches and a partition wall.

The partition wall is between the two furnaces, and is five feet long,

ten feet high, and two feet thick; in front of it is a pillar belonging

in common to the front arches of the furnace on either side, which is

two feet and as many palms thick, three feet and a half wide. The front

arch reaches from this common pillar to another pillar that is common to

the side arch of the same furnace; this arch on the right spans from the

second long wall to the same pillar, which is two feet and as many palms

wide and thick at the bottom. The interior of the front arch is nine

feet and a palm wide, and eight feet high at its highest point; the

interior of the arch which is on the right side, is five feet and a palm

wide, and of equal height to the other, and both the arches are built of

the same height as the partition wall. Imposed upon these arches and the

partition wall are the walls of the chimney; these slope upward, and

thus contract, so that at the upper part, where the fumes are emitted,

the opening is eight feet in length, one foot and three palms in width.

The fourth wall of the chimney is built vertically upon the second long

wall. As the partition wall is common to the two furnaces, so its

superstructure is common to the two chimneys. In this sensible manner

the chimney is built. At the front each furnace is six feet two palms

long, and three feet two palms wide, and a cubit high; the back of each

furnace is against the second long wall, the front being open. The first

furnace is open and sloping at the right side, so that the slags may be

drawn out; the left side is against the partition wall, and has a little

wall built of bricks cemented together with lute; this little wall

protects the partition wall from injury by the fire. On the contrary,

the second furnace has the left side open and the right side is against

the partition wall, where also it has its own little wall which protects

the partition wall from the fire. The front of each furnace is built of

rectangular rocks; the interior of it is filled up with earth. Then in

each of the furnaces at the rear, against the second long wall, is an

aperture through an arch at the back, and in these are fixed the copper

pipes. Each furnace has a round pit, two feet and as many palms wide,

built three feet away from the partition wall. Finally, under the pit of

the furnace, at a depth of a cubit, is the hidden receptacle for

moisture, similar to the others, whose vent penetrates through the

second long wall and slopes upward to the right from the first furnace,

and to the left from the second. If copper is to be made the next day,

then the master cuts out the crucible with a spatula, the blade of which

is three digits wide and as many palms long, the iron handle being two

feet long and one and a half digits in diameter; the wooden handle

inserted into it is round, five feet long and two digits in diameter.

Then, with another cutting spatula, he makes the crucible smooth; the

blade of this spatula is a palm wide and two palms long; its handle,

partly of iron, partly of wood, is similar in every respect to the first

one. Afterward he throws pulverised clay and charcoal into the crucible,

pours water over it, and sweeps it over with a broom into which a stick

is fixed. Then immediately he throws into the crucible a powder, made of

two wheelbarrowsful of sifted charcoal dust, as many wheelbarrowsful of

pulverised clay likewise sifted, and six basketsful of river sand which

has passed through a very fine sieve. This powder, like that used by

smelters, is sprinkled with water and moistened before it is put into

the crucible, so that it may be fashioned by the hands into shapes

similar to snowballs. When it has been put in, the master first kneads

it and makes it smooth with his hands, and then pounds it with two

wooden pestles, each of which is a cubit long; each pestle has a round

head at each end, but one of these is a palm in diameter, the other

three digits; both are thinner in the middle, so that they may be held

in the hand. Then he again throws moistened powder into the crucible,

and again makes it smooth with his hands, and kneads it with his fists

and with the pestles; then, pushing upward and pressing with his

fingers, he makes the edge of the crucible smooth. After the crucible

has been made smooth, he sprinkles in dry charcoal dust, and again

pounds it with the same pestles, at first with the narrow heads, and

afterward with the wider ones. Then he pounds the crucible with a wooden

mallet two feet long, both heads of which are round and three digits in

diameter; its wooden handle is two palms long, and one and a half digits

in diameter. Finally, he throws into the crucible as much pure sifted

ashes as both hands can hold, and pours water into it, and, taking an

old linen rag, he smears the crucible over with the wet ashes. The

crucible is round and sloping. If copper is to be made from the best

quality of "dried" cakes, it is made two feet wide and one deep, but if

from other cakes, it is made a cubit wide and two palms deep. The master

also has an iron band curved at both ends, two palms long and as many

digits wide, and with this he cuts off the edges of the crucible if they

are higher than is necessary. The copper pipe is inclined, and projects

three digits from the wall, and has its upper end and both sides smeared

thick with lute, that it may not be burned; but the underside of the

pipe is smeared thinly with lute, for this side reaches almost to the

edge of the crucible, and when the crucible is full the molten copper

touches it. The wall above the pipe is smeared over with lute, lest that

should be damaged. He does the same to the other side of an iron plate,

which is a foot and three palms long and a foot high; this stands on

stones near the crucible at the side where the hearth slopes, in order

that the slag may run out under it. Others do not place the plates upon

stones, but cut out of the plate underneath a small piece, three digits

long and three digits wide; lest the plate should fall, it is supported

by an iron rod fixed in the wall at a height of two palms and the same

number of digits, and it projects from the wall three palms.

Then with an iron shovel, whose wooden handle is six feet long, he

throws live charcoal into the crucible; or else charcoal, kindled by

means of a few live coals, is added to them. Over the live charcoal he

lays "dried" cakes, which, if they were of copper of the first quality,

weigh all together three _centumpondia_, or three and a half

_centumpondia_; but if they were of copper of the second quality, then

two and a half _centumpondia_; if they were of the third quality, then

two _centumpondia_ only; but if they were of copper of very superior

quality, then they place upon it six _centumpondia_, and in this case

they make the crucible wider and deeper.[24] The lowest "dried" cake is

placed at a distance of two palms from the pipe, the rest at a greater

distance, and when the lower ones are melted the upper ones fall down

and get nearer to the pipe; if they do not fall down they must be pushed

with a shovel. The blade of the shovel is a foot long, three palms and

two digits wide, the iron part of the handle is two palms long, the

wooden part nine feet. Round about the "dried" cakes are placed large

long pieces of charcoal, and in the pipe are placed medium-sized pieces.

When all these things have been arranged in this manner, the fire must

be more violently excited by the blast from the bellows. When the copper

is melting and the coals blaze, the master pushes an iron bar into the

middle of them in order that they may receive the air, and that the

flame can force its way out. This pointed bar is two and a half feet

long, and its wooden handle four feet long. When the cakes are partly

melted, the master, passing out through the door, inspects the crucible

through the bronze pipe, and if he should find that too much of the

"slag" is adhering to the mouth of the pipe, and thus impeding the blast

of the bellows, he inserts the hooked iron bar into the pipe through the

nozzle of the bellows, and, turning this about the mouth of the pipe, he

removes the "slags" from it. The hook on this bar is two digits high;

the iron part of the handle is three feet long; the wooden part is the

same number of palms long. Now it is time to insert the bar under the

iron plate, in order that the "slags" may flow out. When the cakes,

being all melted, have run into the crucible, he takes out a sample of

copper with the third round bar, which is made wholly of iron, and is

three feet long, a digit thick, and has a steel point lest its pores

should absorb the copper. When he has compressed the bellows, he

introduces this bar as quickly as possible into the crucible through the

pipe between the two nozzles, and takes out samples two, three, or four

times, until he finds that the copper is perfectly refined. If the

copper is good it adheres easily to the bar, and two samples suffice; if

it is not good, then many are required. It is necessary to smelt it in

the crucible until the copper adhering to the bar is seen to be of a

brassy colour, and if the upper as well as the lower part of the thin

layer of copper may be easily broken, it signifies that the copper is

perfectly melted; he places the point of the bar on a small iron anvil,

and chips off the thin layer of copper from it with a hammer.[25]

[Illustration 534 (Copper Refining): A--Pointed bar. B--Thin copper

layer. C--Anvil. D--Hammer.]

[Illustration 537 (Copper Refining): A--Crucible. B--Board.

C--Wedge-shaped bar. D--Cakes of copper made by separating them with the

wedge-shaped bar. E--Tongs. F--Tub.]

If the copper is not good, the master draws off the "slags" twice, or

three times if necessary--the first time when some of the cakes have

been melted, the second when all have melted, the third time when the

copper has been heated for some time. If the copper was of good quality,

the "slags" are not drawn off before the operation is finished, but at

the time they are to be drawn off, he depresses the bar over both

bellows, and places over both a stick, a cubit long and a palm wide,

half cut away at the upper part, so that it may pass under the iron pin

fixed at the back in the perforated wood. This he does likewise when the

copper has been completely melted. Then the assistant removes the iron

plate with the tongs; these tongs are four feet three palms long, their

jaws are about a foot in length, and their straight part measures two

palms and three digits, and the curved a palm and a digit. The same

assistant, with the iron shovel, throws and heaps up the larger pieces

of charcoal into that part of the hearth which is against the little

wall which protects the other wall from injury by fire, and partly

extinguishes them by pouring water over them. The master, with a hazel

stick inserted into the crucible, stirs it twice. Afterward he draws

off the slags with a rabble, which consists of an iron blade, wide and

sharp, and of alder-wood; the blade is a digit and a half in width and

three feet long; the wooden handle inserted in its hollow part is the

same number of feet long, and the alder-wood in which the blade is fixed

must have the figure of a rhombus; it must be three palms and a digit

long, a palm and two digits wide, and a palm thick. Subsequently he

takes a broom and sweeps the charcoal dust and small coal over the whole

of the crucible, lest the copper should cool before it flows together;

then, with a third rabble, he cuts off the slags which may adhere to the

edge of the crucible. The blade of this rabble is two palms long and a

palm and one digit wide, the iron part of the handle is a foot and three

palms long, the wooden part six feet. Afterward he again draws off the

slags from the crucible, which the assistant does not quench by pouring

water upon them, as the other slags are usually quenched, but he

sprinkles over them a little water and allows them to cool. If the

copper should bubble, he presses down the bubbles with the rabble. Then

he pours water on the wall and the pipes, that it may flow down warm

into the crucible, for, the copper, if cold water were to be poured over

it while still hot, would spatter about. If a stone, or a piece of lute

or wood, or a damp coal should then fall into it, the crucible would

vomit out all the copper with a loud noise like thunder, and whatever it

touches it injures and sets on fire. Subsequently he lays a curved board

with a notch in it over the front part of the crucible; it is two feet

long, a palm and two digits wide, and a digit thick. Then the copper in

the crucible should be divided into cakes with an iron wedge-shaped bar;

this is three feet long, two digits wide, and steeled on the end for the

distance of two digits, and its wooden handle is three feet long. He

places this bar on the notched board, and, driving it into the copper,

moves it forward and back, and by this means the water flows into the

vacant space in the copper, and he separates the cake from the rest of

the mass. If the copper is not perfectly smelted the cakes will be too

thick, and cannot be taken out of the crucible easily. Each cake is

afterward seized by the assistant with the tongs and plunged into the

water in the tub; the first one is placed aside so that the master may

re-melt it again immediately, for, since some "slags" adhere to it, it

is not as perfect as the subsequent ones; indeed, if the copper is not

of good quality, he places the first two cakes aside. Then, again

pouring water over the wall and the pipes, he separates out the second

cake, which the assistant likewise immerses in water and places on the

ground together with the others separated out in the same way, which he

piles upon them. These, if the copper was of good quality, should be

thirteen or more in number; if it was not of good quality, then fewer.

If the copper was of good quality, this part of the operation, which

indeed is distributed into four parts, is accomplished by the master in

two hours; if of mediocre quality, in two and a half hours; if of bad

quality, in three. The "dried" cakes are re-melted, first in the first

crucible and then in the second. The assistant must, as quickly as

possible, quench all the cakes with water, after they have been cut out

of the second crucible. Afterward with the tongs he replaces in its

proper place the iron plate which was in front of the furnace, and

throws the charcoal back into the crucible with a shovel. Meanwhile the

master, continuing his work, removes the wooden stick from the bars of

the bellows, so that in re-melting the other cakes he may accomplish the

third part of his process; this must be carefully done, for if a

particle from any iron implement should by chance fall into the

crucible, or should be thrown in by any malevolent person, the copper

could not be made until the iron had been consumed, and therefore double

labour would have to be expended upon it. Finally, the assistant

extinguishes all the glowing coals, and chips off the dry lute from the

mouth of the copper pipe with a hammer; one end of this hammer is

pointed, the other round, and it has a wooden handle five feet long.

Because there is danger that the copper would be scattered if the

_pompholyx_ and _spodos_, which adhere to the walls and the hood erected

upon them, should fall into the crucible, he cleans them off in the

meantime. Every week he takes the copper flowers out of the tub, after

having poured off the water, for these fall into it from the cakes when

they are quenched.[26]

The bellows which this master uses differ in size from the others, for

the boards are seven and a half feet long; the back part is three feet

wide; the front, where the head is joined on is a foot, two palms and as

many digits. The head is a cubit and a digit long; the back part of it

is a cubit and a palm wide, and then becomes gradually narrower. The

nozzles of the bellows are bound together by means of an iron chain,

controlled by a thick bar, one end of which penetrates into the ground

against the back of the long wall, and the other end passes under the

beam which is laid upon the foremost perforated beams. These nozzles are

so placed in a copper pipe that they are at a distance of a palm from

the mouth; the mouth should be made three digits in diameter, that the

air may be violently expelled through this narrow aperture.

There now remain the liquation thorns, the ash-coloured copper, the

"slags," and the _cadmia_.[27] Liquation cakes are made from thorns in

the following manner.[28] There are taken three-quarters of a

_centumpondium_ of thorns, which have their origin from the cakes of

copper-lead alloy when lead-silver is liquated, and as many parts of a

_centumpondium_ of the thorns derived from cakes made from once

re-melted thorns by the same method, and to them are added a

_centumpondium_ of de-silverized lead and half a _centumpondium_ of

hearth-lead. If there is in the works plenty of litharge, it is

substituted for the de-silverized lead. One and a half _centumpondia_ of

litharge and hearth-lead is added to the same weight of primary thorns,

and half a _centumpondium_ of thorns which have their origin from

liquation cakes composed of thorns twice re-melted by the same method

(tertiary thorns), and a fourth part of a _centumpondium_ of thorns

which are produced when the exhausted liquation cakes are "dried." By

both methods one single liquation cake is made from three

_centumpondia_. In this manner the smelter makes every day fifteen

liquation cakes, more or less; he takes great care that the metallic

substances, from which the first liquation cake is made, flow down

properly and in due order into the forehearth, before the material of

which the subsequent cake is to be made. Five of these liquation cakes

are put simultaneously into the furnace in which silver-lead is liquated

from copper, they weigh almost fourteen _centumpondia_, and the "slags"

made therefrom usually weigh quite a _centumpondium_. In all the

liquation cakes together there is usually one _libra_ and nearly two

_unciae_ of silver, and in the silver-lead which drips from those cakes,

and weighs seven and a half _centumpondia_, there is in each an _uncia_

and a half of silver. In each of the three _centumpondia_ of liquation

thorns there is almost an _uncia_ of silver, and in the two

_centumpondia_ and a quarter of exhausted liquation cakes there is

altogether one and a half _unciae_; yet this varies greatly for each

variety of thorns, for in the thorns produced from primary liquation

cakes made of copper and lead when silver-lead is liquated from the

copper, and those produced in "drying" the exhausted liquation cakes,

there are almost two _unciae_ of silver; in the others not quite an

_uncia_. There are other thorns besides, of which I will speak a little

further on.

Those in the Carpathian Mountains who make liquation cakes from the

copper "bottoms" which remain after the upper part of the copper is

divided from the lower, in the furnace similar to an oven, produce

thorns when the poor or mediocre silver-lead is liquated from the

copper. These, together with those made of cakes of re-melted thorns, or

made with re-melted litharge, are placed in a heap by themselves; but

those that are made from cakes melted from hearth-lead are placed in a

heap separate from the first, and likewise those produced from "drying"

the exhausted liquation cakes are placed separately; from these thorns

liquation cakes are made. From the first heap they take the fourth part

of a _centumpondium_, from the second the same amount, from the third a

_centumpondium_,--to which thorns are added one and a half

_centumpondia_ of litharge and half a _centumpondium_ of hearth-lead,

and from these, melted in the blast furnace, a liquation cake is made;

each workman makes twenty such cakes every day. But of theirs enough has

been said for the present; I will return to ours.

The ash-coloured copper[29] which is chipped off, as I have stated, from

the "dried" cakes, used some years ago to be mixed with the thorns

produced from liquation of the copper-lead alloy, and contained in

themselves, equally with the first, two _unciae_ of silver; but now it

is mixed with the concentrates washed from the accretions and the other

material. The inhabitants of the Carpathian Mountains melt this kind of

copper in furnaces in which are re-melted the "slags" which flow out

when the copper is refined; but as this soon melts and flows down out of

the furnace, two workmen are required for the work of smelting, one of

whom smelts, while the other takes out the thick cakes from the

forehearth. These cakes are only "dried," and from the "dried" cakes

copper is again made.

The "slags"[30] are melted continually day and night, whether they have

been drawn off from the alloyed metals with a rabble, or whether they

adhered to the forehearth to the thickness of a digit and made it

smaller and were taken off with spatulas. In this manner two or three

liquation cakes are made, and afterward much or little of the "slag,"

skimmed from the molten alloy of copper and lead, is re-melted. Such

liquation cakes should weigh up to three _centumpondia_, in each of

which there is half an _uncia_ of silver. Five cakes are placed at the

same time in the furnace in which argentiferous lead is liquated from

copper, and from these are made lead which contains half an _uncia_ of

silver to the _centumpondium_. The exhausted liquation cakes are laid

upon the other baser exhausted liquation cakes, from both of which

yellow copper is made. The base thorns thus obtained are re-melted with

a few baser "slags," after having been sprinkled with concentrates from

furnace accretions and other material, and in this manner six or seven

liquation cakes are made, each of which weighs some two _centumpondia_.

Five of these are placed at the same time in the furnace in which

silver-lead is liquated from copper; these drip three _centumpondia_ of

lead, each of which contains half an _uncia_ of silver. The basest

thorns thus produced should be re-melted with only a little "slag." The

copper alloyed with lead, which flows down from the furnace into the

forehearth, is poured out with a ladle into oblong copper moulds; these

cakes are "dried" with base exhausted liquation cakes. The thorns they

produce are added to the base thorns, and they are made into cakes

according to the method I have described. From the "dried" cakes they

make copper, of which some add a small portion to the best "dried" cakes

when copper is made from them, in order that by mixing the base copper

with the good it may be sold without loss. The "slags," if they are

utilisable, are re-melted a second and a third time, the cakes made from

them are "dried," and from the "dried" cakes is made copper, which is

mixed with the good copper. The "slags," drawn off by the master who

makes copper out of "dried" cakes, are sifted, and those which fall

through the sieve into a vessel placed underneath are washed; those

which remain in it are emptied into a wheelbarrow and wheeled away to

the blast furnaces, and they are re-melted together with other "slags,"

over which are sprinkled the concentrates from washing the slags or

furnace accretions made at this time. The copper which flows out of the

furnace into the forehearth, is likewise dipped out with a ladle into

oblong copper moulds; in this way nine or ten cakes are made, which are

"dried," together with bad exhausted liquation cakes, and from these

"dried" cakes yellow[31] copper is made.

[Illustration 543 (Copper Refining): A--Furnace. B--Forehearth.

C--Oblong moulds.]

The _cadmia_,[32] as it is called by us, is made from the "slags" which

the master, who makes copper from "dried" cakes, draws off together with

other re-melted base "slags"; for, indeed, if the copper cakes made from

such "slags" are broken, the fragments are called _cadmia_; from this

and yellow copper is made _caldarium_ copper in two ways. For either two

parts of _cadmia_ are mixed with one of yellow copper in the blast

furnaces, and melted; or, on the contrary, two parts of yellow copper

with one of _cadmia_, so that the _cadmia_ and yellow copper may be well

mixed; and the copper which flows down from the furnace into the

forehearth is poured out with a ladle into oblong copper moulds heated

beforehand. These moulds are sprinkled over with charcoal dust before

the _caldarium_ copper is to be poured into them, and the same dust is

sprinkled over the copper when it is poured in, lest the _cadmia_ and

yellow copper should freeze before they have become well mixed. With a

piece of wood the assistant cleanses each cake from the dust, when it is

turned out of the mould. Then he throws it into the tub containing hot

water, for the _caldarium_ copper is finer if quenched in hot water. But

as I have so often made mention of the oblong copper moulds, I must now

speak of them a little; they are a foot and a palm long, the inside is

three palms and a digit wide at the top, and they are rounded at the

bottom.

The concentrates are of two kinds--precious and base.[33] The first are

obtained from the accretions of the blast furnace, when liquation cakes

are made from copper and lead, or from precious liquation thorns, or

from the better quality "slags," or from the best grade of concentrates,

or from the sweepings and bricks of the furnaces in which exhausted

liquation cakes are "dried"; all of these things are crushed and washed,

as I explained in Book VIII. The base concentrates are made from

accretions formed when cakes are cast from base thorns or from the worst

quality of slags. The smelter who makes liquation cakes from the

precious concentrates, adds to them three wheelbarrowsful of litharge

and four barrowsful of hearth-lead and one of ash-coloured copper, from

all of which nine or ten liquation cakes are melted out, of which five

at a time are placed in the furnace in which silver-lead is liquated

from copper; a _centumpondium_ of the lead which drips from these cakes

contains one _uncia_ of silver. The liquation thorns are placed apart

by themselves, of which one basketful is mixed with the precious thorns

to be re-melted. The exhausted liquation cakes are "dried" at the same

time as other good exhausted liquation cakes.

The thorns which are drawn off from the lead, when it is separated from

silver in the cupellation furnace[34], and the hearth-lead which remains

in the crucible in the middle part of the furnaces, together with the

hearth material which has become defective and has absorbed silver-lead,

are all melted together with a little slag in the blast furnaces. The

lead, or rather the silver-lead, which flows from the furnace into the

forehearth, is poured out into copper moulds such as are used by the

refiners; a _centumpondium_ of such lead contains four _unciae_ of

silver, or, if the hearth was defective, it contains more. A small

portion of this material is added to the copper and lead when liquation

cakes are made from them, if more were to be added the alloy would be

much richer than it should be, for which reason the wise foreman of the

works mixes these thorns with other precious thorns. The hearth-lead

which remains in the middle of the crucible, and the hearth material

which absorbs silver-lead, is mixed with other hearth-lead which remains

in the cupellation furnace crucible; and yet some cakes, made rich in

this manner, may be placed again in the cupellation furnaces, together

with the rest of the silver-lead cakes which the refiner has made.

The inhabitants of the Carpathian Mountains, if they have an abundance

of finely crushed copper[35] or lead either made from "slags," or

collected from the furnace in which the exhausted liquation cakes are

dried, or litharge, alloy them in various ways. The "first" alloy

consists of two _centumpondia_ of lead melted out of thorns, litharge,

and thorns made from hearth-lead, and of half a _centumpondium_ each of

lead collected in the furnace in which exhausted liquation cakes are

"dried," and of copper _minutum_, and from these are made liquation

cakes; the task of the smelter is finished when he has made forty

liquation cakes of this kind. The "second" alloy consists of two

_centumpondia_ of litharge, of one and a quarter _centumpondia_ of

de-silverized lead or lead from "slags," and of half a _centumpondium_

of lead made from thorns, and of as much copper _minutum_. The "third"

alloy consists of three _centumpondia_ of litharge and of half a

_centumpondium_ each of de-silverized lead, of lead made from thorns,

and of copper _minutum contusum_. Liquation cakes are made from all

these alloys; the task of the smelters is finished when they have made

thirty cakes.

The process by which cakes are made among the Tyrolese, from which they

separate the silver-lead, I have explained in Book IX.

Silver is separated from iron in the following manner. Equal portions of

iron scales and filings and of _stibium_ are thrown into an earthenware

crucible which, when covered with a lid and sealed, is placed in a

furnace, into which air is blown. When this has melted and again cooled,

the crucible is broken; the button that settles in the bottom of it,

when taken out, is pounded to powder, and the same weight of lead being

added, is mixed and melted in a second crucible; at last this button is

placed in a cupel and the lead is separated from the silver.[36]

There are a great variety of methods by which one metal is separated

from other metals, and the manner in which the same are alloyed I have

explained partly in the eighth book of _De Natura Fossilium_, and partly

I will explain elsewhere. Now I will proceed to the remainder of my

subject.

END OF BOOK XI.

FOOTNOTES:

[1] The whole of this Book is devoted to the subject of the separation

of silver from copper by liquation, except pages 530-9 on copper

refining, and page 544 on the separation of silver from iron. We believe

a brief outline of the liquation process here will refresh the mind of

the reader, and enable him to peruse the Book with more satisfaction.

The fundamental principle of the process is that if a copper-lead alloy,

containing a large excess of lead, be heated in a reducing atmosphere,

above the melting point of lead but below that of copper, the lead will

liquate out and carry with it a large proportion of the silver. As the

results are imperfect, the process cannot be carried through in one

operation, and a large amount of bye-products is created which must be

worked up subsequently. The process, as here described, falls into six

stages. 1st, Melting the copper and lead in a blast furnace to form

"liquation cakes"--that is, the "leading." If the copper contain too

little silver to warrant liquation directly, then the copper is

previously enriched by melting and drawing off from a settling pot the

less argentiferous "tops" from the metal, liquation cakes being made

from the enriched "bottoms." 2nd, Liquation of the argentiferous lead

from the copper. This work was carried out in a special furnace, to

which the admission of air was prevented as much as possible in order to

prevent oxidation. 3rd, "Drying" the residual copper, which retained

some lead, in a furnace with a free admission of air. The temperature

was raised to a higher degree than in the liquation furnace, and the

expelled lead was oxidized. 4th, Cupellation of the argentiferous lead.

5th, Refining of the residual copper from the "drying" furnace by

oxidation of impurities and poling in a "refining furnace." 6th,

Re-alloy and re-liquation of the bye-products. These consist of: _a_,

"slags" from "leading"; _b_, "slags" from "drying"; _c_, "slags" from

refining of the copper. All of these "slags" were mainly lead oxides,

containing some cuprous oxides and silica from the furnace linings; _d_,

"thorns" from liquation; _e_, "thorns" from "drying"; _f_, "thorns" from

skimmings during cupellation; these were again largely lead oxides, but

contained rather more copper and less silica than the "slags"; _g_,

"ash-coloured copper," being scales from the "dried" copper, were

cuprous oxides, containing considerable lead oxides; _h_, concentrates

from furnace accretions, crushed bricks, &c.

The discussion of detailed features of the process has been reserved to

notes attached to the actual text, to which the reader is referred. As

to the general result of liquation, Karsten (see below) estimates the

losses in the liquation of the equivalent of 100 lbs. of argentiferous

copper to amount to 32-35 lbs. of lead and 5 to 6 lbs. of copper. Percy

(see below) quotes results at Lautenthal in the Upper Harz for the years

1857-60, showing losses of 25% of the silver, 9.1% of the copper, and

36.37 lbs. of lead to the 100 lbs. of copper, or say, 16% of the lead;

and a cost of L8 6s. per ton of copper. The theoretical considerations

involved in liquation have not been satisfactorily determined. Those who

may wish to pursue the subject will find repeated descriptions and much

discussion in the following works, which have been freely consulted in

the notes which follow upon particular features of the process. It may

be mentioned that Agricola's treatment of the subject is more able than

any down to the 18th century. Ercker (_Beschreibung Allerfuernemsten

Mineralischen_, etc., Prague, 1574). Lohneys (_Bericht vom Bergwercken_,

etc., Zellerfeldt, 1617). Schlueter (_Gruendlicher Unterricht von

Huette-Werken_, Braunschweig, 1738). _Karsten_ (_System der Metallurgie

V._ and _Archiv fuer Bergbau und Huettenwesen_, 1st series, 1825).

Berthier (_Annales des Mines_, 1825, II.). Percy (Metallurgy of Silver

and Gold, London, 1880).

NOMENCLATURE.--This process held a very prominent position in German

metallurgy for over four centuries, and came to have a well-defined

nomenclature of its own, which has never found complete equivalents in

English, our metallurgical writers to the present day adopting more or

less of the German terms. Agricola apparently found no little difficulty

in adapting Latin words to his purpose, but stubbornly adhered to his

practice of using no German at the expense of long explanatory clauses.

The following table, prepared for convenience in translation, is

reproduced. The German terms are spelled after the manner used in most

English metallurgies, some of them appear in Agricola's Glossary to _De

Re Metallica_.

English. Latin. German.

Blast furnace _Prima fornax_ _Schmeltzofen_

Liquation furnace _Fornax in qua argentum et _Saigernofen_

plumbum ab aere secernuntur_

Drying furnace _Fornax in qua aerei panes _Darrofen_

fathiscentes torrentur_

Refining hearth _Fornax in qua panes aerei _Gaarherd_

torrefacti coquuntur_

Cupellation _Secunda fornax_, or _Treibherd_

furnace _fornax in qua plumbum

ab argento separatur_

Leading _Mistura_ _Frischen_

Liquating _Stillare_, or _distillare_ _Saigern_

"Drying" _Torrere_ _Darren_

Refining _Aes ex panibus torrefactis _Gaarmachen_

conficere_

Liquation cakes _Panes ex aere ac plumbo misti_ _Saigerstock_

Exhausted _Panes fathiscentes_ _Kiehnstock_,

liquation cakes or _Kinstocke_

"Dried" cakes _Panes torrefacti_ _Darrlinge_

Slags from leading _Recrementa_ _Frischschlacke_

(with explanatory phrases)

Slags from drying _Recrementa_ _Darrost_

(with explanatory phrases)

Slags from refining _Recrementa_ _Gaarschlacke_

(with explanatory phrases)

Liquation thorns _Spinae_ _Saigerdoerner_,

(with explanatory phrases) or _Roestdoerner_

Thorns from "drying" _Spinae_ _Darrsoehle_

(with explanatory phrases)

Thorns from _Spinae_ _Abstrich_

cupellation (with explanatory phrases)

Silver-lead or _Stannum_ _Saigerwerk_ or

liquated _saigerblei_

silver-lead

Ash-coloured copper _Aes cinereum_ _Pickschiefer_

or _schifer_

Furnace accretions _Cadmiae_ _Offenbrueche_

or "accretions"

HISTORICAL NOTE.--So far as we are aware, this is the first complete

discussion of this process, although it is briefly mentioned by one

writer before Agricola--that is, by Biringuccio (III, 5, 8), who wrote

ten years before this work was sent to the printer. His account is very

incomplete, for he describes only the bare liquation, and states that

the copper is re-melted with lead and re-liquated until the silver is

sufficiently abstracted. He neither mentions "drying" nor any of the

bye-products. In his directions the silver-lead alloy was cupelled and

the copper ultimately refined, obviously by oxidation and poling,

although he omits the pole. In A.D. 1150 Theophilus (p. 305, Hendrie's

Trans.) describes melting lead out of copper ore, which would be a form

of liquation so far as separation of these two metals is concerned, but

obviously not a process for separating silver from copper. This passage

is quoted in the note on copper smelting (Note on p. 405). A process of

such well-developed and complicated a character must have come from a

period long before Agricola; but further than such a surmise, there

appears little to be recorded. Liquation has been during the last fifty

years displaced by other methods, because it was not only tedious and

expensive, but the losses of metal were considerable.

[2] _Paries_,--"Partition" or "wall." The author uses this term

throughout in distinction to _murus_, usually applying the latter to the

walls of the building and the former to furnace walls, chimney walls,

etc. In order to gain clarity, we have introduced the term "hood" in

distinction to "chimney," and so far as possible refer to the _paries_

of these constructions and furnaces as "side of the furnace," "side of

the hood," etc.

[4] From this point on, the construction of the roofs, in the absence of

illustration, is hopeless of intelligent translation. The constant

repetition of "_tignum_," "_tigillum_," "_trabs_," for at least fifteen

different construction members becomes most hopelessly involved,

especially as the author attempts to distinguish between them in a sort

of "House-that-Jack-built" arrangement of explanatory clauses.

[5] In the original text this is given as the "fifth," a manifest

impossibility.

[6] _Chelae_,--"claws."

[7] If Roman weights, this would be 5.6 short tons, and 7.5 tons if

German _centner_ is meant.

[8] This is, no doubt, a reference to Pliny's statement (XXXIII, 35)

regarding litharge at Puteoli. This passage from Pliny is given in the

footnote on p. 466. Puteoli was situated on the Bay of Naples.

[9] By this expression is apparently meant the "bottoms" produced in

enriching copper, as described on p. 510.

[10] The details of the preparation of liquation cakes--"leading"--were

matters of great concern to the old metallurgists. The size of the

cakes, the proportion of silver in the original copper and in the

liquated lead, the proportion of lead and silver left in the residual

cakes, all had to be reached by a series of compromises among militant

forces. The cakes were generally two and one-half to three and one-half

inches thick and about two feet in diameter, and weighed 225 to 375 lbs.

This size was wonderfully persistent from Agricola down to modern times;

and was, no doubt, based on sound experience. If the cakes were too

small, they required proportionately more fuel and labour; whilst if too

large, the copper began to melt before the maximum lead was liquated.

The ratio of the copper and lead was regulated by the necessity of

enough copper to leave a substantial sponge mass the shape of the

original cake, and not so large a proportion as to imprison the lead.

That is, if the copper be in too small proportion the cakes break down;

and if in too large, then insufficient lead liquates out, and the

extraction of silver decreases. Ercker (p. 106-9) insists on the

equivalent of about 3 copper to 9.5 lead; Lohneys (p. 99), 3 copper to 9

or 10 lead. Schlueter (p. 479, etc.) insists on a ration of 3 copper to

about 11 lead. Kerl (_Handbuch Der Metallurgischen Huettenkunde_, 1855;

Vol. III., p. 116) gives 3 copper to 6 to 7 parts lead. Agricola gives

variable amounts of 3 parts copper to from 8 to 12 parts lead. As to the

ratio of silver in the copper, or to the cakes, there does not, except

the limit of payability, seem to have been any difficulty on the minimum

side. On the other hand, Ercker, Lohneys, Schlueter, and Karsten all

contend that if the silver ran above a certain proportion, the copper

would retain considerable silver. These authors give the outside ratio

of silver permissible for good results in one liquation at what would be

equivalent to 45 to 65 ozs. per ton of cakes, or about 190 to 250 ozs.

per ton on the original copper. It will be seen, however, that

Agricola's cakes greatly exceed these values. A difficulty did arise

when the copper ran low in silver, in that the liquated lead was too

poor to cupel, and in such case the lead was used over again, until it

became rich enough for this purpose. According to Karsten, copper

containing less than an equivalent of 80 to 90 ozs. per ton could not be

liquated profitably, although the Upper Harz copper, according to Kerl,

containing the equivalent of about 50 ozs. per ton, was liquated at a

profit. In such a case the cakes would run only 12 to 14 ozs. per ton.

It will be noticed that in the eight cases given by Agricola the copper

ran from 97 to over 580 ozs. per ton, and in the description of

enrichment of copper "bottoms" the original copper runs 85 ozs., and "it

cannot be separated easily"; as a result, it is raised to 110 ozs. per

ton before treatment. In addition to the following tabulation of the

proportions here given by Agricola, the reader should refer to footnotes

15 and 17, where four more combinations are tabulated. It will be

observed from this table that with the increasing richness of copper an

increased proportion of lead was added, so that the products were of

similar value. It has been assumed (see footnote 13 p. 509), that Roman

weights are intended. It is not to be expected that metallurgical

results of this period will "tie up" with the exactness of the modern

operator's, and it has not been considered necessary to calculate beyond

the nearest pennyweight. Where two or more values are given by the

author the average has been taken.

1ST CHARGE. 2ND CHARGE. 3RD CHARGE. 4TH CHARGE.

Amount of 211.8 lbs. 211.8 lbs. 211.8 lbs. 211.8 lbs.

argentiferous copper

Amount of lead 564.8 " 635.4 " 776.6 " 847.2 "

Weight of each cake 193.5 " 211.5 " 247.1 " 264.75 "

Average value of 56 ozs. 62 ozs. 64 ozs. 66 ozs.

charge 3dwts. 4dwts. 4dwts. 7dwts.

Per cent. of copper 27.2% 25% 21.4% 20%

Average value of 207 ozs. 251 ozs. 299 ozs. 332 ozs.

original copper 4dwts. 3dwts. 15dwts. 3dwts.

per ton

Weight of 423.6 lbs. 494.2 lbs. 635.4 lbs. 706 lbs.

argentiferous lead

liquated out

Average value of 79 ozs. 79 ozs. 79 ozs. 85 ozs.

liquated lead

per ton

Weight of residues 353 lbs. 353 lbs. 353 lbs. 353 lbs.

(residual copper

and thorns)

Average value of 34 ozs. 34 ozs. 34 ozs. 34 ozs. to

residues per ton 38 ozs.

Extraction of 76.5% 73.4% 79% 85.3%

silver into the

argentiferous lead

[11] See p. 356.

[12] An analysis of this "slag" by Karsten (_Archiv_. 1st Series IX, p.

24) showed 63.2% lead oxide, 5.1% cuprous oxide, 20.1% silica (from the

fuel and furnace linings), together with some iron alumina, etc. The

_pompholyx_ and _spodos_ were largely zinc oxide (see note, p. 394).

[13] This description of a _centumpondium_ which weighed either 133-1/3

_librae_, or 146-3/4 _librae_, adds confusion to an already much mixed

subject (see Appendix C.). Assuming the German _pfundt_ to weigh 7,219

troy grains, and the Roman _libra_ 4,946 grains, then a _centner_ would

weigh 145.95 _librae_, which checks up fairly well with the second case;

but under what circumstances a _centner_ can weigh 133-1/3 _librae_ we

are unable to record. At first sight it might appear from this statement

that where Agricola uses the word _centumpondium_ he means the German

_centner_. On the other hand, in the previous five or six pages the

expressions one-third, five-sixths, ten-twelfths of a _libra_ are used,

which are even divisions of the Roman 12 _unciae_ to one _libra_, and

are used where they manifestly mean divisions of 12 units. If Agricola

had in mind the German scale, and were using the _libra_ for a _pfundt_

of 16 _untzen_, these divisions would amount to fractions, and would not

total the _sicilicus_ and _drachma_ quantities given, nor would they

total any of the possibly synonymous divisions of the German _untzen_

(see also page 254).

[14] If we assume Roman weights, the charge in the first case can be

tabulated as follows, and for convenience will be called the fifth

charge:--

5TH CHARGE (3 cakes).

Amount of copper 211.8 lbs.

Amount of lead 635.4 lbs.

Weight of each cake 282.4 lbs.

Average value of charge 218 ozs. 18 dwts.

Per cent. of copper 25%

Average value of original copper per ton 583 ozs. 6 dwts. 16 grs.

Weight of argentiferous lead liquated out 494.2 lbs.

Average value of liquated lead per ton 352 ozs. 8 dwts.

Weight of residues 353 lbs.

Average value of residues per ton 20 ozs. (about).

Extraction of silver into the argentiferous lead 94%

The results given in the second case where the copper contains 2

_librae_ and a _bes_ per _centumpondium_ do not tie together at all, for

each liquation cake should contain 3 _librae_ 9-1/2 _unciae_, instead of

1-1/2 _librae_ and 1/2 _uncia_ of silver.

[15] In this enrichment of copper by the "settling" of the silver in the

molten mass the original copper ran, in the two cases given, 60 ozs. 15

dwts. and 85 ozs. 1 dwt. per ton. The whole charge weighed 2,685 lbs.,

and contained in the second case 114 ozs. Troy, omitting fractions. On

melting, 1,060 lbs. were drawn off as "tops," containing 24 ozs. of

silver, or running 45 ozs. per ton, and there remained 1,625 lbs. of

"bottoms," containing 90 ozs. of silver, or averaging 110 ozs. per ton.

It will be noticed later on in the description of making liquation cakes

from these copper bottoms, that the author alters the value from

one-third _librae_, a _semi-uncia_ and a _drachma_ per _centumpondium_

to one-third of a _libra_, _i.e._, from 110 ozs. to 97 ozs. 4 dwts. per

ton. In the Glossary this furnace is described as a _spleisofen_,

_i.e._, a refining hearth.

[16] The latter part of this paragraph presents great difficulties. The

term "refining furnace" is given in the Latin as the "second furnace,"

an expression usually applied to the cupellation furnace. The whole

question of refining is exhaustively discussed on pages 530 to 539.

Exactly what material is meant by the term red (_rubrum_), yellow

(_fulvum_) and _caldarium_ copper is somewhat uncertain. They are given

in the German text simply as _rot_, _geel_, and _lebeter kupfer_, and

apparently all were "coarse" copper of different characters destined for

the refinery. The author states in _De Natura Fossilium_ (p. 334):

"Copper has a red colour peculiar to itself; this colour in smelted

copper is considered the most excellent. It, however, varies. In some it

is red, as in the copper smelted at Neusohl.... Other copper is prepared

in the smelters where silver is separated from copper, which is called

yellow copper (_luteum_), and is _regulare_. In the same place a dark

yellow copper is made which is called _caldarium_, taking its name among

the Germans from a caldron.... _Regulare_ differs from _caldarium_ in

that the former is not only fusible, but also malleable; while the

latter is, indeed, fusible, but is not ductile, for it breaks when

struck with the hammer." Later on in _De Re Metallica_ (p. 542) he

describes yellow copper as made from "baser" liquation thorns and from

exhausted liquation cakes made from thorns. These products were

necessarily impure, as they contained, among other things, the

concentrates from furnace accretions. Therefore, there was ample source

for zinc, arsenic or other metallics which would lighten the colour.

_Caldarium_ copper is described by Pliny (see note, p. 404), and was, no

doubt, "coarse" copper, and apparently Agricola adopted this term from

that source, as we have found it used nowhere else. On page 542 the

author describes making _caldarium_ copper from a mixture of yellow

copper and a peculiar _cadmia_, which he describes as the "slags" from

refining copper. These "slags," which are the result of oxidation and

poling, would contain almost any of the metallic impurities of the

original ore, antimony, lead, arsenic, zinc, cobalt, etc. Coming from

these two sources the _caldarium_ must have been, indeed, impure.

[17] The liquation of these low-grade copper "bottoms" required that the

liquated lead should be re-used again to make up fresh liquation cakes,

in order that it might eventually become rich enough to warrant

cupellation. In the following table the "poor" silver-lead is designated

(A) the "medium" (B) and the "rich" (C). The three charges here given

are designated sixth, seventh, and eighth for purposes of reference. It

will be seen that the data is insufficient to complete the ninth and

tenth. Moreover, while the author gives directions for making four

cakes, he says the charge consists of five, and it has, therefore, been

necessary to reduce the volume of products given to this basis.

6TH CHARGE. 7TH CHARGE. 8TH CHARGE.

Amount of copper 176.5 lbs. 176.5 lbs. 176.5 lbs.

bottoms

Amount of lead 282.4 lbs. 564.8 lbs. 635.4 lbs.

(slags) of (A) of (B)

Amount of 494.2 lbs. 211.8 lbs. 141.2 lbs. (A)

de-silverized lead

Weight of each cake 238.3 lbs. 238.3 lbs. 238.3 lbs.

Average value of 22 ozs. 35 ozs. 50 ozs.

charge per ton 5dwts. 15dwts. 5dwts.

Per cent. of copper 18.5% 18.5% 18.5%

Average value per 97 ozs. 97 ozs. 97 ozs.

ton original copper 4dwts. 4dwts. 4dwts.

Average value per 90 ozs. 28 ozs. 28 ozs.

ton of 2dwts. (slags) 5dwts. (A) 5dwts. (A)

Average value per 3 ozs. 3 ozs. 42 ozs.

ton of 1dwt. (lead) 1dwt. (lead) 10dwts. (B)

Weight of liquated 550.6 lbs.

lead

Average value of 28 ozs. 42 ozs. 63 ozs.

the liquated lead 5dwts. (A) 10dwts. (B) 16dwts. (C)

per ton

Weight of exhausted 225.9 lbs.

liquation cakes

Average value of 12 ozs.

the exhausted 3dwts.

liquation cakes

per ton

Weight of liquation 169.4 lbs.

thorns

Average value of 18 ozs.

the liquation 4dwts.

thorns per ton

Extraction of 71%

silver into the

liquated lead