Dissolve pech-blende in aqua regia, precipitate its copper by
sulphuretted hydrogen, boil the liquid along with nitric acid, in order
to transform all the uranium into uranic acid. Next boil it along with
cupric oxide, which precipitates only the uranic and ferric oxides.
Redissolve the precipitate in nitric acid, and boil the solution with
mercuric oxide, which does not precipitate the ferric oxide. Finally,
separate the copper and the mercury from the uranium, by means of
sulphuretted hydrogen. In this process we may substitute plumbic oxide
for the cupric oxide, and succeed equally well.
Knowledge, like the above, of the elective affinities and habitudes of
chemical bodies, simple and compound, imparts to its possessor an
irresistible power over the unions and disunions of the elements, which
he can exercise with certainty in effecting innumerable transformations
in the arts.
DECREPITATION, (Eng. and Fr.; _Verknistern_, Germ.) is the crackling
noise, attended with the flying asunder of their parts, made by several
salts and minerals, when heated. It is caused by the unequal sudden
expansion of their substance by the heat. Sulphate of baryta, chloride
of sodium, calcareous spar, nitrate of baryta, and many more bodies
which contain no water, decrepitate most violently, separating at the
natural joints of their crystalline structure. Some chemists have
preposterously enough ascribed the phenomenon to the expansion of the
combined water into steam. What a specimen of inductive philosophy!
DEFECATION, (Eng. and Fr.; _Klaren_, Germ.) the freeing from dregs or
impurities.
DEFLAGRATION, (Eng. and Fr.; _Verpuffung_, Germ.) the sudden blazing up
of a combustible; as of a charcoal or sulphur when thrown into melted
nitre.
DELPHINIA. The vegeto-alkaline principle of the _Delphinium
staphysagria_, or stavesacre. It is poisonous.
DELIQUESCENT, (_Zerfliessen_, Germ.) is said of a solid which attracts
so much moisture from the air as to become spontaneously soft or liquid;
such as potash and muriate of lime.
DEPHLEGMATION is the process by which liquids are deprived of their
watery particles. It is applied chiefly to spirituous liquors, and is
now nearly obsolete, as involving the alchemistical notion of a peculiar
principle called phlegm.
DEPHLOGISTICATED; deprived of phlogiston,--formerly supposed to be the
common combustible principle. It is nearly synonymous with oxygenated.
The idea originally attached to the word having proceeded from false
logic, the word itself should never be used either in science or
manufactures.
DEPILATORY. (_Depilatoire_, Fr.; _Enthaarensmittel_, Germ.) is the name
of any substance capable of removing hairs from the human skin without
injuring its texture. They act either mechanically or chemically. The
first are commonly glutinous plasters formed of pitch and rosin, which
stick so closely to the part of the skin where they are applied, that
when removed, they tear away the hairs with them. This method is more
painful, but less dangerous than the other, which consists in the
solvent action of a menstruum, so energetic as to penetrate the pores of
the skin, and destroy the bulbous roots of the hairs. This is composed
either of caustic alkalis, sulphuret of baryta, or arsenical
preparations. Certain vegetable juices have also been recommended for
the same purpose; as spurge and acacia. The bruised eggs of ants have
likewise been prescribed. But the _oriental rusma_ yields to nothing in
depilatory power. Gadet de Gassincourt has published in the
_Dictionnaire des Sciences Medicales_, the following recipe for
preparing it.
Mix two ounces of quicklime, with half an ounce of orpiment or realgar,
(sulphuret of arsenic;) boil that mixture in one pound of strong
alkaline lye, then try its strength by dipping a feather into it, and
when the flue falls off, the _rusma_ is quite strong enough. It is
applied to the human skin by a momentary friction, followed by washing
with warm water. Such a caustic liquid should be used with the greatest
circumspection, beginning with it somewhat diluted. A soap is sometimes
made with lard and the above ingredients; or soft soap is combined with
them; in either case to form a depilatory pommade. Occasionally one
ounce of orpiment is taken to eight ounces of quicklime, or two to
twelve, or three to fifteen; the last mixture being of course the most
active. Its causticity may be tempered by the addition of one eighth of
starch or rye flour, so as to form a soft paste, which being laid upon
the hairy spot for a few minutes, usually carries away the hairs with
it.
The _rusma_ should never be applied but to a small surface at a time,
for independently of the risk of corroding the skin, dangerous
consequences might ensue from absorption of the arsenic.
DETONATION. See FULMINATING, for the mode of preparing detonating powder
for the percussion caps of fire-arms.
DEUTOXIDE literally means the second oxide, but is usually employed to
denote a compound containing two atoms or two prime equivalents of
oxygen to one or more of a metal. Thus we say deutoxide of copper, and
deutoxide of mercury. Berzelius has abbreviated this expression by
adopting the principles of the French nomenclature of 1787; according to
which the higher stage of oxidizement is characterized by the
termination _ic_, and the lower by _ous_, and he writes accordingly
cupric and mercuric, to designate the deutoxides of these two metals;
cuprous and mercurous to designate their protoxides. I have adopted this
nomenclature in the article DECOMPOSITION, and in some other parts of
this Dictionary, as being short and sufficiently precise.
DEXTRINE, is a matter of a gummy appearance into which the interior
substance of the molecules of starch are converted, through the
influence of diastase or acids. It derives its name from the
circumstance that it turns, more than any other body, the plane of
polarization to the right hand. It is white, insipid, without smell,
transparent in thin plates, friable, with a glassy fracture when well
dried. It is not altered by the heat of boiling water, but at 280° F. it
becomes brown, and acquires the flavour of toasted bread. It is not
coloured by iodine, like starch, it does not form muric acid with the
nitric, as common gum does, and it is transformed into grape sugar, when
heated along with dilute sulphuric acid or diastase.
Dextrine is much employed by the French pastrycooks and confectioners;
it is a good substitute for gum arabic in medicine. For the conversion
of potato or other starch into dextrine, by the action of diastase, see
this article.
DIAMOND. Since this body is merely a condensed form of carbon, it cannot
in a chemical classification be ranked among stones; but as it forms in
commerce the most precious of the gems, it claims our first attention in
a practical treatise on the arts. Diamonds are distinguishable by a
great many peculiar properties, very remarkable and easily recognized,
both in their rough state, and when cut and polished. Their most
absolute and constant character is a degree of hardness superior to that
of every mineral, whence diamonds scratch all other bodies, and are
scratched by none. Their peculiar adamantine lustre, not easy to define,
but readily distinguishable by the eye from that of every other gem, is
their most obvious feature. Their specific gravity is 3·55. Whether
rough or polished, diamonds acquire by friction, positive electricity,
but do not retain it for more than half an hour. The natural form of
diamonds is derivable from an octahedron, and they never present
crystals having one axis longer than the other. Their structure is very
perceptibly lamellar, and therefore, notwithstanding their great
hardness, they are brittle and give way in the line of their cleavage,
affording a direct means of arriving at their primitive form, the
regular octahedron.
The diamond possesses either single or double refraction, according to
its different crystalline forms; its refractive power on light is far
greater than it ought to be in the ratio of its density; the index of
refraction being 2·44, whence Newton long ago supposed it to consist of
inflammable matter. Its various forms in nature present a circumstance
peculiar to this body; its faces are rarely terminated by planes, like
most other native crystals, but they are often rounded off, and the
edges between them are curved. When these secondary faces are
attentively examined with a lens, we remark that they are marked with
striæ, sometimes very fine and almost imperceptible, but at others well
defined; and that these striæ are parallel to the edges of the
octahedron, and consequently to those of the plates that are applied on
the primitive faces of this figure.
Diamonds are usually colourless and transparent; when coloured, their
ordinary tint verges upon yellow, or smoke-yellow, approaching sometimes
to blackish-brown. Green diamonds are next to yellow the most common;
the blue possess rarely a lively hue, but they are much esteemed in
Scotland. The rose or pink diamonds are the most valued of the coloured
kind, and exceed sometimes in price the most limpid; though generally
speaking the latter are the most highly prized.
The geological locality of the diamond seems to be in diluvial gravel,
and among conglomerate rocks; consisting principally of fragments of
quartz, or rolled pebbles of quartz mixed with ferruginous sand, which
compose sometimes hard aggregated masses. This kind of formation is
called _cascalho_ in Brazil. Its accompanying minerals are few in
number, being merely black oxide of iron, micaceous iron ore, pisiform
iron ore, fragments of slaty jasper, several varieties of quartz,
principally amethyst. In Mr. Heuland’s splendid collection there was a
Brazilian diamond imbedded in brown iron ore; another in the same,
belonging to M. Schuch, librarian to the Crown Princess of Portugal; and
in the cabinet of M. Eschwege there is a mass of brown iron ore,
containing a diamond in the drusy cavity of a green mineral, conjectured
to be arseniate of iron. From these facts it may be inferred with much
probability that the matrix or original repository of the diamond of
Brazil is brown iron ore, which occurs in beds of slaty quartzose
micaceous iron ore, or in beds composed of iron-glance and magnetic iron
ore, both of which are apparently subordinate in that country to
primitive clay slate.
The loose earth containing diamonds lies always a little way beneath the
surface of the soil, towards the lower outlet of broad valleys, rather
than upon the ridges of the adjoining hills.
Only two _places_ on the earth can be adduced with certainty, as diamond
mines, or rather districts; a portion of the Indian peninsula, and of
Brazil.
India has been celebrated from the most remote antiquity as the country
of diamonds. Its principal mines are in the kingdoms of Golconda and
Visapour, extending from Cape Comorin to Bengal, at the foot of a chain
of mountains called the _Orixa_, which appear to belong to the trap rock
formation. In all the Indian diamond soils, these gems are so dispersed,
that they are rarely found directly, even in searching the richest
spots, because they are enveloped in an earthy crust, which must be
removed before they can be seen. The stony matter is therefore broken
into pieces, and is then, as well as the looser earth, washed in basins
scooped out on purpose. The gravel thus washed is collected, spread out
on a smooth piece of ground, and left to dry. The diamonds are now
recognized by their sparkling in the sun, and are picked out from the
stones.
The diamond mines of Brazil were discovered in 1728, in the district of
Serro-do-Frio. The ground in which they are imbedded has the most
perfect resemblance to that of the East Indies, where the diamonds
occur. It is a solid or friable conglomerate, consisting chiefly of a
ferruginous sand, which encloses fragments of various magnitude of
yellow and bluish quartz, of schistose jasper, and grains of gold
disseminated with oligist iron ore; all mineral matters different from
those that constitute the neighbouring mountains; this conglomerate, or
species of pudding-stone, almost always superficial, occurs sometimes at
a considerable height on the mountainous table-land. The most celebrated
diamond mine is that of Mandarga, on the Jigitonhonha, in the district
of Serro-do-Frio to the north of Rio-Janeiro. The river Jigitonhonha,
three times broader than the Seine at Paris, and from 3 to 9 feet deep,
is made nearly dry, by drawing the waters off with sluices at a certain
season; and the _cascalho_ or diamond-gravel is removed from the channel
by various mechanical means, to be washed elsewhere at leisure. This
cascalho, the same as the matrix of the gold mines, is collected in the
dry season, to be searched into during the rainy; for which purpose it
is formed into little mounds of 15 or 16 tons weight each. The washing
is carried on beneath an oblong shed, by means of a stream of water
admitted in determinate quantities into boxes containing the cascalho. A
negro washer is attached to each box; inspectors are placed at regular
distances on elevated stools, and whenever a negro has found a diamond,
he rises up and exhibits it. If it weighs 17-1/2 carats, he receives his
liberty. Many precautions are taken to prevent the negroes from
secreting the diamonds. Each squad of workmen consists of 200 negroes,
with a surgeon and an almoner or priest.
The flat lands on either side of the river are equally rich in diamonds
over their whole surface, so that it becomes very easy to estimate what
a piece of ground not yet washed may produce.
It is said that the diamonds surrounded with a greenish crust, are of
the _first_ water, or are the most limpid when cut. The diamonds
received in the different mines of the district, are deposited once a
month in the treasury of Tejuco; and the amount of what was thus
delivered from 1801 to 1806, may be estimated at about 18 or 19 thousand
carats _per annum_.
On the banks of the torrent called Rio-Pardo, there is another mine of
diamonds. The ground presents a great many friable rocks of
pudding-stone, distributed in irregular strata. It is chiefly in the bed
of this stream, that masses of cascalho occur, peculiarly rich in
diamonds. They are much esteemed, particularly those of a greenish-blue
colour. The ores that accompany the diamond at Rio-Pardo differ somewhat
from those of the washing grounds of Mandanga, for they contain no
pisiform iron ore; but a great many pebbles of slaty jasper. This table
land seems to be very high, probably not less than 5500 feet above the
level of the sea.
Tocaya, a principal village of Minas-Novas, is 34 leagues to the
north-east of Tejuco, in an acute angle of the confluence of the
Jigitonhonha, and the Rio-Grande. In the bed of the streamlets which
fall westward into the Jigitonhonha, those rolled white topazes are
found which are known under the name of _minas-novas_ with _blue
topazes_, and aquamarine beryls. In the same country are found the
beautiful cymophanes or chrysoberyls so much prized in Brazil. And it is
from the cantons of Indaia and Abaite that the largest diamonds of
Brazil come; yet they have not so pure a water as those of the district
of Serro-do-Frio, but incline a little to the lemon yellow.
Diamonds are said to come also from the interior of the island of
Borneo, on the banks of the river Succadan, and from the peninsula of
Malacca.
It is known that many minerals become phosphorescent by heat, or
exposure to the sun’s light. Diamonds possess this property, but all not
in equal degree, and certain precautions must be observed to make it
manifest. Diamonds need to be exposed to the sunbeam for a certain time,
in order to become self-luminous; or to the blue rays of the prismatic
spectrum, which augment still more the faculty of shining in the dark.
Diamonds susceptible of phosphorescence exhibit it either after a heat
not raised to redness, or the electric discharge. They possess not only
a great refractive power in the mean ray of light, but a high dispersive
agency, which enables them to throw out the most varied and vivid
colours in multiplied directions.
Louis de Berquem discovered in 1476, the art of cutting diamonds by
rubbing them against one another, and of polishing them with their own
powder. These operations may be abridged by two methods: 1. by availing
ourselves of the direction of the laminæ of the diamond to split them in
that direction, and thus to produce several facets. This process is
called cleaving the diamond. Some, which appear to be _macle_ crystals,
resist this mechanical division, and are called _diamonds of nature_. 2.
by sawing the diamonds by means of a very delicate wire, coated with
diamond powder.
_Diamonds_ take precedence of every gem for the purposes of dress and
decoration; and hence the price attached to those of a pure water,
increases in so rapid a proportion, that beyond a certain term, there is
no rule of commercial valuation. The largest diamond that is known seems
to be that of the Rajah of Mattan, in the East Indies. It is of the
purest water, and weighs 367 carats, or at the rate of 4 grains to a
carat, upwards of 3 ounces troy. It is shaped like an egg, with an
indented hollow near the smaller end; it was discovered at Landak about
100 years ago; and though the possession of it has cost several wars, it
has remained in the Mattan family for 90 years. A governor of Batavia,
after ascertaining the qualities of the gem, wished to be the purchaser,
and offered 150,000 dollars for it, besides two war brigs with their
guns and ammunition, together with a certain number of great guns, and a
quantity of powder and shot. But this diamond possessed such celebrity
in India, and was regarded as a talisman involving the fortunes of the
Rajah and his family, that he refused to part with it at any price.
The diamond possessed in the time of the traveller Tavernier, by the
emperor of Mogul, a kingdom now no more, weighed 279 carats, and was
reckoned worth upwards of 400,000_l._ sterling. It was said to have lost
the half of its original weight in the cutting. After these prodigious
gems, the next are:--1. That of the emperor of Russia, bought by the
late empress Catherine, which weighs 193 carats. It is said to be of the
size of a pigeon’s egg, and to have been bought for 90,000_l._, besides
an annuity to the Greek merchant of 4000_l._ It is reported that the
above diamond formed one of the eyes of the famous statue of Sheringan,
in the temple of Brama, and that a French grenadier, who had deserted
into the Malabar service, found the means of robbing the pagoda of this
precious gem; and escaped with it to Madras, where he disposed of it to
a ship captain for 2,000_l._, who resold it to a Jew for 12,000_l._ From
him it was transferred for a large sum to the Greek merchant. 2. That of
the emperor of Austria, which weighs 139 carats, and has a slightly
yellowish hue. It has, however, been valued at 100,000_l._ 3. That of
the king of France, called the Regent or Pitt diamond, remarkable for
its form and its perfect limpidity. Although it weighs only 136 carats,
its fine qualities have caused it to be valued at 160,000_l._ though it
cost only 100,000_l._
The largest diamond furnished by Brazil, now in possession of the crown
of Portugal, weighs, according to the highest estimates, 120 carats. It
was found in the streamlet of Abaïte, in a clay-slate district.
The diamonds possessed of no extraordinary magnitude, but of a good form
and a pure water, may be valued by a certain standard rule. In a
brilliant, or rose-diamond of regular proportions, so much is cut away
that the weight of the polished gem does not exceed one half the weight
of the diamond in the rough state; whence the value of a cut diamond is
esteemed equal to that of a similar rough diamond of double weight,
exclusive of the cost of workmanship. The weight and value of diamonds
is reckoned by carats of 4 grains each; and the comparative value of two
diamonds of equal quality but different weights, is as the squares of
these weights respectively. The average price of rough diamonds that are
worth working, is about 2_l._ for one of a single carat; but as a
polished diamond of one carat must have taken one of 2 carats, its price
in the rough state is double the square of 2_l._, or 8_l._ Therefore, to
estimate the value of a wrought diamond, ascertain its weight in carats,
double that weight, and multiply the square of this product by 2_l._
Hence, a wrought diamond of 1 carat is worth _£_ 8
2 -- 32
3 -- 72
4 -- 128
5 -- 200
6 -- 288
7 -- 392
8 -- 512
9 -- 612
10 -- 800
20 -- 3200,
beyond which weight the prices can no longer rise in this geometrical
progression, from the small number of purchasers of such expensive toys.
A very trifling spot or flaw of any kind, lowers exceedingly the
commercial value of a diamond.
Diamonds are used not only as decorative gems, but for more useful
purposes, as for cutting glass by the glazier, and all kinds of hard
stones by the lapidary.
On the structure of the glazier’s diamond, we possess some very
interesting observations and reflections by Dr. Wollaston. He remarks,
that the hardest substances brought to a sharp point scratch glass,
indeed, but do not cut it, and that diamond alone possessed that
property; which he ascribes to the peculiarity of its crystallization in
rounded faces, and curvilinear edges. For glass-cutting, those rough
diamonds are always selected which are sharply crystallized, hence
called diamond sparks; but cut diamonds are never used. The inclination
to be given to a set diamond in cutting glass is comprised within very
narrow limits; and it ought, moreover, to be moved in the direction of
one of its angles. The curvilinear edge adjoining the curved faces,
entering as a wedge into the furrow opened up by itself, thus tends to
separate the parts of the glass; and in order that the crack which
causes the separation of the vitreous particles may take place, the
diamond must be held almost perpendicular to the surface of the glass.
The Doctor proved this theory by an experiment. If, by suitable cutting
with the wheel, we make the edges of a spinel ruby, or corundum-telesie
(sapphire) curvilinear, and the adjacent faces curved, these stones will
cut glass as well as a glazier’s diamond, but being less hard than it,
they will not preserve this property so long. He found that upon giving
the surface of even a fragment of flint the same shape as that of the
cutting diamond, it acquired the same property; but, from its relative
softness, was of little duration. The depth to which the fissure caused
by the glazier’s diamond penetrates, does not seem to exceed the
two-hundredth of an inch.
I shall here introduce Mr. Milburn’s valuable observations on the choice
of rough diamonds, as published in his work on _Oriental Commerce_.
The colour should be perfectly crystalline, resembling a drop of clear
spring water, in the middle of which you will perceive a strong light,
playing with a great deal of spirit. If the coat be smooth and bright,
with a little tincture of green in it, it is not the worse, and seldom
proves bad, but if there is a mixture of yellow with green, then beware
of it; it is a soft greasy stone, and will prove bad.
If the stone has a rough coat, so that you can hardly see through it,
and the coat be white and look as if it were rough by art, and clear of
flaws or veins, and no blemish cast in the body of the stone, (which may
be discovered by holding it against the light) the stone will prove
good.
It often happens that a stone will appear of a reddish hue on the
outward coat, not unlike the colour of rusty iron, yet by looking
through it against the light, you may observe the heart of the stone to
be white (and if there be any black spots, or flaws, or veins in it,
they may be discovered by a true eye, although the coat of the stone be
the same), and such stones are generally good and clear.
If a diamond appears of a greenish bright coat, resembling a piece of
green glass, inclining to black, it generally proves hard, and seldom
bad; such stones have been known to have been of the first water, and
seldom worse than the second; but if any tincture of yellow seems to be
mixed with it, you may depend on its being a very bad stone.
All stones of a milky cast, whether the coat be bright or dull, if ever
so little inclining to a bluish cast, are naturally soft, and in danger
of being flawed in the cutting; and though they should have the good
fortune to escape, yet they will prove dead and milky, and turn to no
account.
All diamonds of cinnamon colour are dubious; but if of a bright coat
mixed with a little green, then they are certainly bad, and are
accounted among the worst of colours. You will meet with a great many
diamonds of a rough cinnamon-coloured coat, opaque; this sort is
generally very hard, and, when cut, contain a great deal of life and
spirit; but the colour is very uncertain; it is sometimes white,
sometimes brown, and sometimes of a fine yellow. Rough diamonds are
frequently _beamy_, that is look fair to the eye, yet are so full of
veins to the centre, that no art or labour can polish them. A good
diamond should never contain small spots of a white or gray colour of a
nebulous form; it should be free from small reddish and brownish grains,
that sometimes occur on their surface, or in their interior. A good
diamond should split readily in the direction of the cleavage; it
sometimes happens, however, that the folia are curved, as is the case in
twin crystals. When this happens, the stone does not readily cut and
polish, and is therefore of inferior value.
In the cut and polished gem, the thickness must always bear a certain
proportion to the breadth. It must not be too thin nor thick; for, when
too thin, it loses much of its fire, and appears not unlike glass.
The term _carat_ is said to be derived from the name of a bean, the
produce of a species of _erythina_, a native of the district of
Shangallas, in Africa; a famous mart of gold-dust. The tree is called
_kuara_, a word signifying sun in the language of the country; because
it bears flowers and fruit of a flame colour. As the dry seeds of this
pod are always of nearly uniform weight, the savages have used them from
time immemorial to weigh gold. The beans were transported into India, at
an ancient period, and have been long employed there for weighing
diamonds. The carat of the civilized world is, in fact, an imaginary
weight, consisting of 4 nominal grains, a little lighter than 4 grains
troy (_poids de marc_); it requires 74 carat grains and 1/16 to
equipoise 72 of the other.
In valuing a cut diamond, we must reckon that one half of its weight has
been lost in the lapidary’s hands; whence its weight in this state
should be doubled before we calculate its price by the general rule for
estimating diamonds. The French multiply by 48 the square of this
weight, and they call the product in francs the value of the diamond.
Thus, for example, a cut diamond of 10 carats would be worth (10 × 2)² ×
48 = 19,200 francs, or 768_l._, allowing only 25 francs to the pound
sterling.
The diamond mines of Brazil have brought to its government, from the
year 173~ till 1814, 3,023,000 carats; being at the average rate
annually of 36,000 carats, or a little more than 16 libs., weight. They
have not been so productive in the later years of that period; for,
according to Mr. Mawe, between 1801 and 1806, only 115,675 carats were
obtained, being 19,279 a year. The actual expenses incurred by the
government, during this interval, was 4,419,700 francs; and, deducting
the production in gold from the washings of the diamond gravel, or
_cascalho_, it is found that the rough diamonds cost in exploration, per
carat, 38 francs 20 c., or nearly 31_s._ British money. The contraband
is supposed to amount to one third of the above legitimate trade. Brazil
is almost the only country where diamonds are mined at the present day;
it sends annually to Europe from 25 to 30 thousand carats, or from 10 to
16-1/2 libs.
DIAMONDS, _cutting of_. Although the diamond is the hardest of all known
substances, yet it may be split by a steel tool, provided a blow be
applied; but this requires a perfect knowledge of the structure, because
it will only yield to such means in certain directions. This
circumstance prevents the workman from forming facettes or planes
generally, by the process of splitting; he is therefore obliged to
resort to the process of abrasion, which is technically called cutting.
The process of cutting is effected by fixing the diamond to be cut on
the end of a stick, or handle, in a small ball of cement, that part
which is to be reduced being left to project. Another diamond is also
fixed in a similar manner; and the two stones being rubbed against each
other with considerable force, they are mutually abraded, flat surfaces,
or facettes, being thereby produced. Other facettes are formed by
shifting the diamonds into fresh positions in the cement, and when a
sufficient number are produced, they are fit for polishing. The stones,
when cut, are fixed for this purpose, by imbedding them in soft solder,
contained in a small copper cup, the part, or facette, to be polished,
being left to protrude.
A flat circular plate of cast-iron is then charged with the powder
produced during the abrasion of the diamonds; and by this means a tool
is formed which is capable of producing the exquisite lustre so much
admired on a finely-polished gem. Those diamonds that are unfit for
working, on account of the imperfection of their lustre or colour, are
sold, for various purposes, under the technical name of Bort. Stones of
this kind are frequently broken in a steel mortar, by repeated blows,
until they are reduced to a fine powder, which is used to charge metal
plates, of various kinds, for the use of jewellers, lapidaries, and
others. Bort, in this state of preparation, is incapable of polishing
any gems; but it is used to produce flat surfaces on rubies and other
precious stones.
Fine drills are made of small splinters of bort, which are used for
drilling small holes in rubies, and other hard stones, for the use of
watch-jewellers, gold and silver wire-drawers, and others, who require
very fine holes drilled in such substances. These drills are also used
to pierce holes in china, where rivets are to be inserted; also for
piercing holes in artificial enamel teeth, or any vitreous substances,
however hard.
DIAMOND MICROSCOPES, were first suggested by Dr. Goring, and have been
well executed by Mr. Pritchard. Previous to grinding a diamond into a
spherical figure, it should be ground flat and parallel upon both sides,
that by looking through it, as opticians try flint glass, we may see
whether it has a double or triple refractive power, as many have, which
would render it useless as a lens. Among the 14 different crystalline
forms of the diamond, probably the octahedron and the cube are the only
ones that will give single vision. It will, in many cases, be advisable
to grind diamond lenses, plano-convex, both because this figure gives a
low spherical aberration, and because it saves the trouble of grinding
one side of the gem. A concave tool of cast iron, paved with diamond
powder, hammered into it by a hardened steel punch, was employed by Mr.
Pritchard. This ingenious artist succeeded in completing a double convex
of equal radii, of about 1/25 of an inch focus, bearing an aperture of
1/30 of an inch with distinctness upon opaque objects, and its entire
diameter upon transparent ones. This lens gives vision with a trifling
chromatic aberration; in other respects, like Dr. Goring’s Amician
reflector, but without its darkness, its light is said to be superior to
that of any compound microscope whatever, acting with the same power,
and the same angle of aperture. The advantage of seeing an object
without _aberration_ by the interposition of only a single magnifier,
instead of looking at a picture of it with an eye-glass, is evident. We
thus have a simple direct view, whereby we shall see more accurately and
minutely the real texture of objects.
DIAPER, is the name of a kind of cloth, used chiefly for table linen. It
is known among the French by the name of _toile fourré_, and is
ornamented with the most extensive figures of any kind of tweeled
cloth, excepting damask. The mounting of a loom for working diaper is,
in principle, much the same as a draw-loom, but the figures being less
extensive, the mounting is more simple, and is wrought entirely by the
weaver, without the aid of any other person. As tweeled cloths, of any
number of leaves, are only interwoven at those intervals when one of the
leaves is raised, the woof above, and the warp below, is kept floating
or flushed, until the intersection takes place. Of consequence, the
floating yarn above, appears across the fabric, and that below
longitudinally. This property of tweeled cloths is applied to form the
ornamental figures of all kinds of tweeled goods, merely by reversing
the floating yarn when necessary. In the simpler patterns, this is
effected by a few additional leaves of treddles; but when the range of
pattern becomes too great to render this convenient, an apparatus called
a _back harness_ is employed, and the cloth woven with this mounting is
called diaper. Diapers are generally five-leaf tweels, that is to say,
every warp floats under four threads of woof, and is raised, and of
course interwoven with the fifth. This is done either successively,
forming diagonals at 45° upon the cloth, or by intervals of two threads,
which is called the broken tweel. The latter is generally, if not
universally adopted in the manufacture of diaper. The reason of
preferring the broken to the regular tweel, where ornaments are to be
formed, is very obvious. The whole depending upon reversed flushing to
give the appearance of oblique or diagonal lines, through either, would
destroy much of the effect, and materially injure the beauty of the
fabric. The broken tweel, on the contrary, restores to the tweeled cloth
a great similarity of appearance to plain, or alternately interwoven
fabrics, and, at the same time, preserves the facility of producing
ornaments by reversing the flushing. The simplest kinds of reversed
tweels will be found described under TEXTILE FABRICS.
DIASTASE. This curious substance, extracted by water from crushed malt,
and precipitated from that infusion by alcohol, as is described under
FERMENTATION, has been made the subject of new researches by M. Guerin
Varry. The conclusions deducible from his interesting experiments are
the following:--
1. One part of diastase, dissolved in 30 parts of cold water, put with
408 parts of potato starch out of contact of air, did not exercise the
slightest action upon this substance in the course of 63 days, under a
temperature varying from 68° to 79° Fahr.
2. Two parts of diastase do not in the course of an hour, cause the
globules of three parts of starch to burst, at a temperature approaching
very nearly to that of the hot water which bursts them into a paste. It
follows that diastase acts no part in the process of germination,
towards eliminating the teguments of the starch, or transforming its
interior portion into sugar, and a gummy matter assimilated by plants.
3. Diastase liquefies and saccharifies the paste of starch without
absorption or disengagement of gas; a reaction which takes place equally
in vacuo, as in the open air.
4. 100 parts of starch made into a paste with 39 times their weight of
water, mixed with 6·13 parts of diastase dissolved in 40 parts of water,
and kept for an hour between 140° and 149° Fahr., afforded 86·91 parts
of sugar.
5. A paste containing 100 parts of starch, and 1393 parts of water, put
in contact with 12·25 parts of diastase dissolved in 367 parts of cold
water, having been maintained at 68° Fahr. during 24 hours, produced
77·64 parts of sugar.
6. The preceding experiment, repeated at the temperature of melting ice,
afforded at the end of 2 hours, 11·82 parts of sugar.
7. The most favourable proportions and circumstances for the production
of a great quantity of sugar, are a slight excess of diastase or barley
malt, (at least 25 per cent. of the latter), about 50 parts of water to
one of starch, and a temperature between 140° and 149° Fahr. It is of
the greatest consequence for the saccharification to take place as
speedily as possible, so that the sugar produced may not be left in
contact with much gummy matter (_dextrine_), in which case, the diastase
will not convert the latter into sugar. In fact, the liquefaction and
saccharification should proceed simultaneously.
8. The sugar of starch, prepared either with diastase, or sulphuric
acid, crystallizes in cauliflowers, or in prisms with rhomboidal facets.
It has the same composition as sugar of grapes.
9. Diastase even in excess does not saccharify the gummy matter
dissolved in the water along with the starch sugar, but when the gum is
insulated, it is convertible almost entirely into sugar.
10. Gum arabic, cane sugar, and beer yeast, suffer no change from
diastase.
11. A watery solution of diastase readily decomposes on keeping, either
in contact or out of contact of air.
12. When starch-sugar, whether obtained by means of diastase or
sulphuric acid, is submitted to the spirituous fermentation, the sum of
the weights of the alcohol, carbonic acid, and water of crystallization
of the sugar, is less than the weight of the sugar by about 3-1/2 per
cent. This difference proceeds in a great measure from the formation of
some acetic acid, lactic acid, volatile oil, and probably some other
unknown products in the act of fermentation.
DIMITY, is a kind of cotton cloth originally imported from India, and
now manufactured in great quantities in various parts of Britain,
especially in Lancashire. Dr. Johnson calls it _dimmity_, and describes
it as a kind of fustian. The distinction between fustian and dimity
seems to be, that the former designates a common tweeled cotton cloth of
a stout fabric, which receives no ornament in the loom, but is most
frequently dyed after being woven. Dimity is also a stout cotton cloth,
but not usually of so thick a texture; and is ornamented in the loom,
either with raised stripes or fancy figures, is seldom dyed, but usually
worn white, as for bed and bed-room furniture. The striped dimities are
the most common, they require less labour in weaving than the others;
and the mounting of the loom being more simple, and consequently less
expensive, they can be sold at much lower rates. See TEXTILE FABRICS,
for particular details of the plan of mounting them.
DIES FOR STAMPING, (_Coins_, Fr.; _Münzstempeln_, Germ.) The first
circumstance that claims particular attention in the manufacture of
dies, is the selection of the best kind of steel for the purpose, and
this must in some measure be left to the experience of the die-forger,
who, if well skilled in his art, will be able to form a tolerably
correct judgment of the fitness of the metal for the purpose, by the
manner in which it works upon the anvil. It should be rather
fine-grained than otherwise, and above all things perfectly even and
uniform in its texture, and free from spots and patches finer or coarser
than the general mass. But the very fine and uniform steel with a silky
fracture, which is so much esteemed for some of the purposes of cutlery,
is unfit for our present purpose, from the extreme facility with which
it acquires great hardness by pressure, and its liability to cracks and
flaws. The very coarse-grained, or highly crystalline steel, is also
equally objectionable; it acquires fissures under the die-press, and
seldom admits of being equally and properly hardened. The object,
therefore, is to select a steel of a medium quality as to fineness of
texture, not easily acted upon by dilute sulphuric acid, and exhibiting
an uniform texture when its surface is washed over with a little
aqua-fortis, by which its freedom from pins of iron, and other
irregularities of composition, is sufficiently indicated.
The best kind of steel being thus selected, and properly forged at a
high heat into the rough die, it is softened by very careful annealing,
and in that state, having been smoothed externally, and brought to a
table in the turning lathe, it is delivered to the engraver.
The process of annealing the die consists in heating it to a bright
cherry red, and suffering it to cool gradually, which is best effected
by bedding it in a crucible or iron pot of coarsely-powdered charcoal,
that of animal substances being generally preferred. In this operation
it is sometimes supposed that the die, or at least its superficial
parts, becomes super-carbonized, or highly-converted steel, as it is
sometimes called; but experience does not justify such an opinion, and I
believe the composition of the die is scarcely, certainly not
materially, affected by the process, for it does not remain long enough
in the fire for the purpose.
The engraver usually commences his labours by working out the device
with small steel tools, in intaglio; he rarely begins in relief (though
this is sometimes done); and having ultimately completed his design, and
satisfied himself of its general effect and correctness, by impressions
in clay, and dabs, or casts in type metal, the die is ready for the
important operation of hardening, which, from various causes, a few of
which I shall enumerate, is a process of much risk and difficulty; for
should any accident now occur, the labour of many months may be
seriously injured, or even rendered quite useless.
The process of hardening soft steel is in itself very simple, though not
very easily explained upon mechanical or chemical principles. We know by
experience, that it is a property of this highly valuable substance, to
become excessively hard, if heated and suddenly cooled; if, therefore,
we heat a bar of soft malleable and ductile steel red hot, and then
suddenly quench it in a large quantity of cold water, it not only
becomes hard, but fragile and brittle. But as a die is a mass of steel
of considerable dimensions, this hardening is an operation attended by
many and peculiar difficulties, more especially as we have at the same
time to attend to the careful preservation of the engraving. This is
effected by covering the engraved face of the die with a protecting
face, composed of fixed oil of any kind, thickened with powdered
charcoal: some persons add pipe-clay, others use a pulp of garlic, but
pure lamp-black and linseed oil answer the purpose perfectly. This is
thinly spread upon the work of the die, which, if requisite, may be
further defended by an iron ring; the die is then placed with its face
downwards in a crucible, and completely surrounded by powdered charcoal.
It is heated to a suitable temperature, that is, about cherry red, and
in that state is taken out with proper tongs, and plunged into a body of
cold water, of such magnitude as not to become materially increased in
temperature; here it is rapidly moved about, until all noise ceases, and
then left in the water till quite cool. In this process it should
produce a bubbling and hissing noise; if it pipes and sings, we may
generally apprehend a crack or fissure.
No process has been found to answer better than the above simple and
common mode of hardening dies, though others have had repeated and fair
trials. It has been proposed to keep up currents and eddies of cold
water in the hardening cistern, by means of delivery-pipes, coming from
a height; and to subject the hot die, with its face uppermost, to a
sudden and copious current of water, let upon it from a large pipe,
supplied from a high reservoir; but these means have not in any way
proved more successful, either in saving the die, or in giving it any
good qualities. It will be recollected, from the form of the die, that
it is necessarily only, as it were, case-hardened, the hardest strata
being outside, and the softer ones within, which envelope a core,
something in the manner of the successive coats of an onion; an
arrangement which we sometimes have an opportunity of seeing displayed
in dies which have been smashed by a violent blow.
The hardening having been effected, and the die being for the time safe,
some further steps may be taken for its protection; one of these
consists in a very mild kind of tempering, produced by putting it into
water, gradually raised to the boiling point, till heated throughout,
and then suffering it gradually to cool. This operation renders the die
less apt to crack in very cold weather. A great safeguard is also
obtained by thrusting the cold die into a red-hot iron ring, which just
fits it in that state, and which, by contracting as it cools, keeps its
parts together under considerable pressure, preventing the spreading of
external cracks and fissures, and often enabling us to employ a split or
die for obtaining punches, which would break to pieces without the
protecting ring.
If the die has been successfully hardened, and the protecting paste has
done its duty, by preserving the face from all injury and oxidizement,
or burning, as it is usually called, it is now to be cleaned and
polished, and in this state constitutes what is technically called a
MATRIX: it may of course be used as a multiplier of medals, coins, or
impressions, but it is not generally thus employed, for fear of
accidents happening to it in the coining press, and because the artist
has seldom perfected his work upon it in this state. It is, therefore,
resorted to for the purpose of finishing a PUNCH, or steel impression
for relief. For this purpose a proper block of steel is selected, of the
same quality, and with the same precautions as before, and being
carefully annealed, or softened, is turned like the matrix, perfectly
true and flat at the bottom, and obtusely conical at top. In this state,
its conical surface is carefully compressed by powerful and proper
machinery upon the matrix, which being very hard, soon allows it to
receive the commencement of an impression; but in thus receiving the
impression, it becomes itself so hard by condensation of texture as to
require during the operation to be repeatedly annealed, or softened,
otherwise it would split into small superficial fissures, or would
injure the matrix; much practical skill is therefore required in taking
this impression, and the punch, at each annealing, must be carefully
protected, so that the work may not be injured.
Thus, after repeated blows in the die-press, and frequent annealing, the
impression from the matrix is at length perfected, or brought completely
up, and having been retouched by the engraver, is turned, hardened, and
collared, like the matrix, of which it is now a complete impression in
relief, and, as we have before said, is called a punch.
This punch becomes an inexhaustible parent of dies, without further
reference to the original matrix; for now by impressing upon it plugs of
soft steel, and by pursuing with them an exactly similar operation to
that by which the punch itself was obtained, we procure impressions from
it to any amount, which of course are fac-similes of the matrix, and
these dies being turned, hardened, polished, and, if necessary,
tempered, are employed for the purposes of coinage.
The distinction between striking medals, and common coin, is very
essential, and the work upon the dies is accordingly adjusted to each.
Medals are usually in very high relief, and the effect is produced by a
succession of blows; and as the metal in which they are struck, be it
gold, silver, or copper, acquires considerable hardness at each stroke
of the press, they are repeatedly annealed during the process of
bringing them up. In a beautiful medal, which Mr. Wyon some time since
completed for the Royal Navy College, the obverse represents a head of
the King, in very bold relief; it required thirty blows of a very
powerful press to complete the impression, and it was necessary to
anneal each medal after every third blow, so that they went ten times
into the fire for that purpose. In striking a coin or medal, the lateral
spread of the metal, which otherwise would ooze out as it were from
between the dies, is prevented by the application of a steel collar,
accurately turned to the dimensions of the dies, and which, when left
plain, gives to the edge of the piece a finished and polished
appearance; it is sometimes grooved, or milled, or otherwise
ornamented, and occasionally lettered, in which case it is made in three
separate and moveable pieces, confined by a ring, into which they are
most accurately fitted, and so adjusted that the metal may be forced
into the letters by its lateral spread, at the same time that the coin
receives the blow of the screw-press.
Coins are generally completed by one blow of the coining-press. These
presses are worked in the Royal Mint by machinery, so contrived that
they shall strike, upon an average, sixty blows in a minute; the blank
piece, previously properly prepared and annealed, being placed between
the dies by part of the same mechanism.
The number of pieces which may be struck by a single die of good steel,
properly hardened and duly tempered, not unfrequently amounts at the
Mint to between three and four hundred thousand, but the average
consumption of dies is of course much greater, owing to the variable
qualities of steel, and to the casualties to which the dies are liable:
thus, the upper and lower die are often violently struck together, owing
to an error in the layer-on, or in that part of the machinery which
ought to put the blank into its place, but which now and then fails so
to do. This accident very commonly arises from the boy who superintends
the press neglecting to feed the hopper of the layer-on with blank
pieces. If a die is too hard, it is apt to break or split, and is
especially subject to fissures, which run from letter to letter upon the
edge. If too soft, it swells, and the collar will not rise and fall upon
it, or it sinks in the centre, and the work becomes distorted and
faulty. He, therefore, who supplies the dies for an extensive coinage,
has many accidents and difficulties to encounter. There are eight
presses at the Mint, frequently at work for ten hours each day, and the
destruction of eight pair of dies per day (one pair for each press) may
be considered a fair average result, though they much more frequently
fall short of, than exceed this proportion. It must be remembered, that
each press produces 3600 pieces per hour, but, making allowance for
occasional stoppages, we may reckon the daily produce of each press at
30,000 pieces; the eight presses therefore will furnish a diurnal
average of 240,000 pieces.
DIGESTER, is the name of a strong kettle or pot of small dimensions,
made very strong, and mounted with a safety valve in its top. Papin, the
contriver of this apparatus, used it for subjecting bones, cartilages,
&c. to the solvent action of high-pressure steam, or highly heated
water, whereby he proposed to facilitate their digestion in the stomach.
This contrivance is the origin of the French cookery pans, called
_autoclaves_, because the lid is self-keyed, or becomes steam-tight by
turning it round under clamps or ears at the sides, having been
previously ground with emery to fit the edge of the pot exactly. In some
autoclaves the lid is merely laid on with a fillet of linen as a lute,
and then secured in its place by means of a screw bearing down upon its
centre from an arched bar above. The safety valve is loaded either by a
weight placed vertically upon it, or by of a lever of the second kind
pressing near its fulcrum, and acted upon by a weight which may be made
to bear upon any point of its graduated arm.
Chevreul has made a useful application of the digester to vegetable
analysis. His instrument consists of a strong copper cylinder, into
which enters a tight cylinder of silver, having its edge turned over at
right angles to the axis of the cylinder, so as to form the rim of the
digester. A segment of a copper sphere, also lined with silver stops the
aperture of the silver cylinder, being applied closely to its rim. It
has a conical valve pressed with a spiral spring, of any desired force,
estimated by a steelyard. This spring is enclosed within a brass box
perforated with four holes; which may be screwed into a tapped orifice
in the top of the digester. A tube screwed into another hole serves to
conduct away the condensable vapours at pleasure into a Woulfe’s
apparatus.
DISTILLATION, (Eng. and Fr.; _Branntweinbrennerei_, Germ.) means, in the
commercial language of this country, the manufacture of intoxicating
spirits; under which are comprehended the four processes, of _mashing_
the vegetable materials, _cooling_ the worts, exciting the vinous
_fermentation_, and separating by a peculiar vessel called a _still_,
the alcohol combined with more or less water. This art of evoking the
fiery demon of drunkenness from his attempered state in wine and beer,
was unknown to the ancient Greeks and Romans. It seems to have been
invented by the barbarians of the north of Europe, as a solace to their
cold and humid clime; and was first made known to the southern nations
in the writings of Arnoldus de Villa Nova, and his pupil, Raymond Lully
of Majorca, who declares this admirable essence of wine to be an
emanation of the Divinity, an element newly revealed to man, but hid
from antiquity, because the human race were then too young to need this
beverage, destined to revive the energies of modern decrepitude. He
further imagined that the discovery of this _aqua vitæ_, as it was
called, indicated the approaching consummation of all things--the end of
this world. However much he erred as to the value of this remarkable
essence, he truly predicted its vast influence upon humanity, since to
both civilized and savage nations it has realized greater ills than were
threatened in the fabled box of Pandora.
I shall consider in this place the first three of these subjects,
reserving for the article STILL an account of the construction and use
of that apparatus.
Whiskey, from the Irish word Usquebaugh, is the British name of the
spirituous liquor manufactured by our distillers, and corresponds to the
_Eau de vie_ of the French, and the _Branntwein_ of the Germans. It is
generated by that intestine change which grape juice and other
glutino-saccharine liquids spontaneously undergo when exposed to the
atmosphere at common temperatures; the theory of which will be expounded
under the article FERMENTATION. The production of whiskey depends upon
the simple fact, that when any vinous fluid is boiled, the alcohol being
very volatile, evaporates first, and may thereby be separated from the
aqueous vegetable infusion in which it took its birth. Sugar is the only
substance which can be transformed into alcohol. Whatsoever fruits,
seeds, or roots afford juices or extracts capable of conversion into
vinous liquor, either contain sugar ready formed, or starch susceptible
of acquiring the saccharine state by proper treatment. In common
language, the intoxicating liquor obtained from the sweet juices of
fruits is called wine; and that from the infusions of farinaceous seeds,
beer; though there is no real difference between them in chemical
constitution. A similar beverage, though probably less palatable, is
procurable from the juices and infusions of many roots, by the process
of fermentation. Wine, cyder, beer, and fermented wash of every kind,
when distilled, yields an identical intoxicating spirit, which differs
in these different cases merely in flavour, in consequence of the
presence of a minute quantity of volatile oils of different odours.
I. The juices of sweet fruits contain a glutinous ingredient which acts
as a ferment in causing their spontaneous change into a vinous
condition; but the infusions of seeds, even in their germinated or
malted state, require the addition of a glutinous substance called
yeast, to excite the best fermentation. In the fabrication of wine or
beer for drinking, the fermentative action should be arrested before all
the fruity saccharum is decomposed; nor should it on any account be
suffered to pass into the acetous stage; whereas for making distillery
wash, that action should be promoted as long as the proportion of
alcohol is increased, because the formation of a little acetic acid is
not injurious to the quality of the distilled spirit, but rather
improves its flavour by the addition of acetic ether, while all the
undecomposed sugar is lost. Distillers operate upon the saccharine
matter from corn of various kinds in two methods; in the first they draw
off a pure watery extract from the grain, and subject this species of
wort to fermentation; in the second they ferment and distil the infused
mass of grains. The former is the practice of the distillers in the
United Kingdom, and is preferable on many accounts; the latter, which is
adopted in Germany, Holland, and the north of Europe, is less
economical, more uncertain in the product, and affords a cruder spirit,
in consequence of the fetid volatile oil evolved from the husks in the
still. The substances employed by the distillers may be distributed into
the following classes:--
1. Saccharine juices. At the head of these stands cane-juice, which
fresh from the mill contains from 12 to 16 per cent. of raw sugar, and
like the must of the grape enters into the vinous fermentation without
the addition of yeast, affording the species of spirit called Rum, which
is possessed of a peculiar aroma derived from an essential oil in the
cane. An inferior sort of rum is fabricated from molasses, mixed with
the skimmings and washings of the sugar pans. When molasses or treacle
is diluted with twenty times its weight of warm water, and when the
mixture has cooled to 78° F., if one twelfth of its weight of yeast be
added, fermentation will speedily ensue, and an ardent spirit will be
generated, which when distilled has none of the aroma of rum; proving
this to reside in the immediate juice or substance of the cane, and to
be dissipated at the high temperature employed in the production of
molasses. Though the cane juice will spontaneously undergo the vinous
fermentation, it does so more slowly and irregularly than the routine of
business requires, and therefore is quickened by the addition of the
lees of a preceding distillation. So sensible are the rum distillers of
the advantage of such a plan, that they soak woollen cloths in the yeast
of the fermenting vats, in order to preserve a ferment from one sugar
season to another. In Jamaica and some other of our colonies, 50 gallons
of spent wash or lees are mixed with 6 gallons of molasses, 36 gallons
of sugar-pan skimmings (a substance rich in aroma), and 8 gallons of
water; in which mixture there is about one twelfth part of solid
saccharum. Those who attend more to the quality than the quantity of
their rum, will use a smaller proportion of the spent wash, which is
always empyreumatic, and imparts more or less of its odour to the spirit
distilled from it. The fermentation is seldom complete in less than 9
days, and most commonly it requires from 12 to 15; the period being
dependent upon the capacity of the fermenting tun, and the quality of
its contents. The liquid now becomes clear, the froth having fallen to
the bottom, and few bubbles of gas are extricated from it, while its
specific gravity is reduced from 1·050 down to 0·992. The sooner it is
subjected to distillation after this period the better, to prevent the
loss of alcohol by the supervention of the acetous stage of
fermentation, an accident very liable to happen in the sugar colonies.
The crude spirit obtained from the large single still at the first
operation, is rectified in a smaller still. About 114 gallons of rum,
proof strength, specific gravity 0·920, are obtained from 1200 gallons
of wash. Now these 1200 gallons weigh 12,600 libs., and contain nearly
one eighth of their weight of sugar = 1575 libs.; which should yield
nearly its own weight of proof spirit, whose bulk is = 1575/0·92 = 1712
pound measures = 171·2 gallons; whereas only 114 are obtained; proving
the processes to be conducted in a manner far from economical, even with
every reasonable allowance.
Mr Edwards gives the following estimate: “The total amount of sweets
from an estate in Jamaica which makes 200 hogsheads of sugar, is 16,666
gallons. The wash set at the rate of 12 per cent. sweets, should return
34,720 gallons of low wines, which should give 14,412 gallons of rum, or
131 puncheons of 110 gallons each.”
By my own experiments on the quantity of proof spirit obtainable from
molasses by fermentation (afterwards to be detailed), one gallon of
sweets should yield one gallon of spirit; and hence the above 16,666
gallons should have afforded the same bulk of rum. But here we are left
somewhat in the dark, by not knowing the specific gravity of the rum
spoken of by Mr. Edwards. The only light let in upon us is when he
mentions rum oil-proof, that is, a spirit in which olive oil will sink;
indicating a density nearly the same with our actual excise proof, for
olive oil at 60° F. has the specific gravity 0·919. When a solution of
sugar of the proper strength is mixed with wine lees, and fermented, it
affords a spirit by distillation not of the rum, but of the brandy
flavour.
The sweet juices of palm trees and cocoa nuts, as also of the maple, and
ash, birch, &c., when treated like cane juice, afford vinous liquors
from which ardent spirits, under various names, are obtained; as
_arrack_, &c.; the quantity being about 50 pounds of alcohol of 0·825
for every 100 pounds of solid saccharine extract present. Honey
similarly treated affords the metheglin so much prized by our ancestors.
Good whey, freed from curd by boiling, will yield 4 per cent. of spirit
of wine, when fermented with the addition of a little yeast.
2. The juices of apples, pears, currants, and such fruits, afford by
fermentation quantities of alcohol proportional to the sugar they
contain. But the quality of the spirit is much better when it is
distilled from vinous liquids of a certain age, than from recently
fermented must. Cherries are employed in Germany, and other parts of the
Continent, for making a high-flavoured spirit called _Kirsch-wasser_, or
cherry water. The fully ripe fruit is crushed by a roller press, or an
edge-stone mill, along with the kernels; the pulp is fermented in a
mass, the liquid part is then drawn off, and distilled. More or less
prussic acid enters from the kernels into this spirit, which renders it
very injurious, as a liquor, to many constitutions. I was once nearly
poisoned by swallowing a wine glass of it in the valley of Chamouni. The
ripened red fruit of the mountain ash constitutes a good material for
vinous fermentation. The juice being mixed with some water and a little
yeast, affords when well fermented, according to Hermstaedt, 12 pounds,
or 1-1/2 gallons, of alcohol from 2 bushels of the ripe berries.
3. Many roots contain sugar, particularly beet, from which no less than
7 per cent. of it may be extracted by judicious means. Hermstaedt
recommends to mash the steam boiled clean roots, and add to the paste
two-thirds of its weight of boiling water, and a thirtieth of its weight
of ground malt, mixing the materials well, and then leaving them three
hours in a covered vessel. The mixture must now be passed through a wire
sieve, with meshes of one-third of an inch square each; the residuum is
washed with a little cold water, and, when the temperature has fallen to
77° F., the proper quantity of yeast must be added, and the fermentation
suffered to proceed in a covered tun. In 5 or 6 days it will be
complete, and will afford by distillation, from 100 pounds of beet root,
about 10 or 12 pounds of proof spirits. Carrots and parsnips, when
similarly treated, yield a considerable quantity of alcohol.