THE WINDOWS AND LEAD-WORK.
We must now give to our dwelling-house those conveniences which call
for the services of the glazier and the plumber. These two occupations
are so often combined by the same tradesman, and the two classes of
operations thereby resulting are both so necessary to the finishing of
the _exterior_ of a house, that we may conveniently treat of them in
one chapter.
Introduction of Glass-Windows.
Among the features which distinguish modern houses from those existing
in the early ages of English history, few have been more conducive to
comfort than the adoption of _Glass-Windows_. Before the employment of
that invaluable substance--glass--for this purpose, windows consisted
either of uncovered holes in the wall of a house, whereby in order to
admit light, the cold would also gain admittance; or else they were
holes covered with oiled skin, oiled paper, thin horn, or some other
partially transparent material, which would admit a dim light, and yet
exclude wind and rain. It is only by placing ourselves in a room thus
lighted, that we can form a correct idea of the increase of comfort
resulting from the use of glass instead of such imperfectly transparent
substances. The slow and imperfect modes of making glass soon after its
introduction necessarily gave it a high value, and it could only be
employed by the wealthy; but its price has gradually so much lessened,
and its claim to a place among the necessaries of life so generally
felt and acknowledged, that there are now but few persons in England,
except those moving in the very humblest ranks of society, who have not
a room with a glazed window.
The Manufacture of Window Glass.
The glass with which windows are generally glazed, is called _Crown
glass_. It is formed of different materials in different manufactories.
In some instances the materials consist of fine white sand, carbonate
of lime, carbonate of soda, and clippings or waste pieces of old glass;
while in other cases they consist of white sand, pearl-ash, saltpetre,
borax, and arsenic, in certain proportions. On this point we shall
not dwell, for almost every manufacturer has a favourite receipt of
his own. Whatever substances are employed, they are intimately mixed
before being melted. The melting takes place in large crucibles or
melting pots, made of a particular kind of clay capable of enduring
intense heat. Several such crucibles are placed in a furnace, a little
door being situate in the furnace opposite to each crucible. Through
this door the materials are introduced and are suffered to melt; and
as soon as these become melted, other portions of the materials are
added, until the crucible contains a given amount of melted material.
A curious effect is then observable. Although most or all of the
materials are nearly opaque in their separate states, it is found that
when they are all melted together, they form a transparent liquid,
which is _glass_.
It requires about forty-eight hours of intense heat to bring the
whole contents of the crucible to a liquid state. During this period,
a quantity of dross or impurity, called _sandiver_ or _glass gall_,
collects at the surface, and is carefully removed; it is afterwards
sold to refiners of metals, who use it as a flux. The temperature of
the furnace is then gradually lowered, by which means the glass loses
sufficient heat to assume a pasty consistence, which is more convenient
for the workman than if it were perfectly fluid.
The glass maker then stands before the door of the furnace, exposed
to an intensity of heat such as few persons can adequately conceive,
and dips into the pasty mass of glass the end of a hollow iron tube
about five feet long. On withdrawing the tube, a portion of glass is
found adhering to it, and this is made to equalize itself round the
circumference of the tube by turning the latter rapidly round. The
workman then applies his mouth to the other end, and blows through the
tube, whereby the pasty mass is made to assume a hollow globular form
at the remote end of the tube. This process is continued for some time
and with great dexterity, until the globe has attained a considerable
diameter and a proportionably small thickness. The globe is then
somewhat flattened at the side opposite to the tube by pressing it upon
a hard plane surface; and a solid iron rod, called a _punt_, having a
small quantity of melted glass at the end, is applied to the centre of
the flattened side opposite to the tube, to which it adheres; the tube
is then removed by wetting the glass near the point of union with the
tube, leaving a small circular hole. During these processes the glass
is repeatedly heated by holding it for a few minutes at the door of the
furnace, in order that it may retain the requisite degree of softness.
The _punt_, with the flattened globe of glass at its end, is then
rapidly whirled round in a manner nearly resembling that in which a mop
is twirled. By this motion, the globe becomes more and more flattened
and extended in diameter, until at length, not being able longer to
retain its shape, it bursts open, and spreads out in the form of a
flat circular sheet of glass three or four feet in diameter. There
is perhaps nothing in the whole range of the mechanical arts more
astonishing to a spectator than this process, and there are few that
require, from the workman, more of that dexterity of hand which can
only be acquired by long practice. The workman continues to whirl the
sheet of glass round,--gradually receding from the furnace,--until it
is sufficiently set or solidified to retain its form. The punt is then,
by a dextrous movement, detached from the centre of the sheet, leaving
that bulb which is known as the “bull’s eye,” or the “knot.” The sheet
is placed in an annealing oven, the temperature of which is lowered by
slow degrees until cold; for it is found that glass is less brittle
when it has been allowed to cool gradually than when the cooling has
been rapid. Considerable care is required to regulate the temperature
of the annealing oven; if the heat be too great the softened glass will
bend: if the heat be insufficient the plates are liable to crack, or
they prove so brittle that when they come to be used, the glazier will
not be able to divide the glass so as to suit his purposes. Indeed,
the management of the heat in the manufacture of crown glass requires
so much care and skill that few workmen produce an article of the same
value, even though working at the same furnace; hence crown glass is
known in the market as firsts, seconds, thirds, and fourths; the fourth
quality producing less than one-half of the price of the first.
We have not interrupted this description, to refer to engravings; but
we may now illustrate it by the following cuts representing the glass
in eight different stages of its formation.
1st. The melted glass attached to the tube, and worked on a board.
[Illustration]
2nd. The workman blowing through the tube, to expand the glass.
[Illustration]
3rd. Whirling it rapidly at the mouth of the furnace.
[Illustration]
4th. Transferring it from the hollow tube to the solid punt.
[Illustration]
5th and 6th. Successive stages of expansion, by constant and rapid
rotation.
[Illustration]
[Illustration]
7th. Final expansion into a flat circular sheet.
[Illustration]
8th. The sheet of glass, held on a kind of fork, being placed into the
annealing oven.
[Illustration]
When cold, the sheets of glass are cut into two unequal pieces, one
of which contains the _knot_, and are packed with straw in wooden
_crates_, in which they are forwarded to the warehouses, and from
thence to the glaziers.
As plate glass is sometimes used for windows, a slight notice of it
seems to be necessary in this place, in order that the reader may have
a clear idea of the difference between these two descriptions of window
glass.
The manufacture of plate glass is confined to very few hands, and
great reluctance is manifested by the proprietors to permit visitors
to inspect their works. The late Mr. Parkes, however, was permitted to
visit the works of the British Plate Glass Company, at Ravenhead, and
has recorded his observations in one of his valuable chemical essays,
from which the following details are taken.
In the preparation of plate glass the materials are selected with
greater care than in any other branch of the glass manufacture. The
materials employed are sand of the finest and whitest kind, soda, and
lime. Manganese and oxide of cobalt are also used for the purpose of
destroying colour, which they do by the curious, and at first view,
paradoxical property each has of imparting colour. The manganese has
the effect of a slight tinge of red, the cobalt of blue; while the sand
and alkali produce a slight yellow tinge; and thus these three colours
(being those which naturally produce white light) by proper combination
in the glass neutralise each other, and the result is an almost
perfectly transparent material.
The process of filling the pots and fusing the materials is similar
to that already described for crown glass. The crucibles are of two
kinds; the larger ones wherein the glass is melted, are called _pots_,
and because these when full of glass are too bulky and heavy to be
moved, smaller ones, called _cuvettes_, are employed. These are kept
empty in the furnaces, exposed to the full degree of heat, so that when
the glass is ready for casting and is transferred to them, they may not
greatly lower its temperature.
The subsequent operations are very well described in an abstract of
Mr. Parkes’s essay, given by the writer of the volume on Glass and
Porcelain, in the _Cabinet Cyclopædia_.
“When the glass is thoroughly refined, the cuvette--which must be
perfectly clean, and, as already mentioned, of a temperature equal
with that of the glass--is filled in the following manner:--A copper
ladle, ten to twelve inches in diameter, fixed to an iron handle seven
feet long, is plunged into the glass pot, and brought up filled with
melted glass, which is transferred to the cuvette; the ladle during
this transference is supported upon a strong iron rest, placed under
its bottom, and held by two other workmen. This precaution is necessary
to prevent the bending and giving way of the red-hot copper under the
weight of fluid glass which it contains. When by successive ladlings
the cuvette is filled, it is suffered to remain during some hours in
the furnace, that the air bubbles formed by this disturbance may have
time to rise and disperse; an effect which is ascertained to have
ensued by the inspection of samples withdrawn from time to time for the
purpose.
“Another essential part of the apparatus consists in flat tables
whereon the plates of glass are cast. These tables have perfectly
smooth and level metallic surfaces, of suitable dimensions and
solidity, supported by masonry. At St. Gobain, and formerly also at
Ravenhead, these tables were made of copper; the reason assigned
for preferring this metal being, that it does not discolour the hot
melted glass, while the use of iron was thought to be accompanied by
this disadvantage. These copper tables were very costly, both from
the nature of their material, and the labour bestowed in grinding
and polishing their surfaces; and as the sudden access of heat that
accompanied the pouring over them of such a torrent of melted glass
occasioned the metal frequently to crack, the tables were by such an
accident rendered useless. The British Plate Glass Company having
experienced several disasters of this nature, its directors determined
upon making trial of iron; and they accordingly procured a plate to be
cast, fifteen feet long, nine feet wide, and six inches thick, which
has fully answered the intended purpose--having, during several years
of constant use, stood uninjured through all the sudden, and violent
alternations of temperature to which it has been exposed. This table is
so massive, weighing nearly fourteen tons, that it became necessary to
construct a carriage purposely for its conveyance from the iron foundry
to the glasshouse. It is supported on castors, for the convenience of
readily removing it towards the mouths of the different annealing ovens.
“The foundry at Ravenhead wherein this table is used is said to be
the largest room under one roof that has ever yet been erected in
this kingdom; it is 339 feet long, 155 feet wide, and proportionately
lofty. Westminster Hall, to which the superiority in this respect
is so commonly ascribed, is smaller--its length being 300 and its
breadth only 100 feet. The melting furnaces, which are ranged down the
centre, occupy about one-third of the whole area of this apartment.
The annealing ovens are placed in two rows, one on each side of the
foundry, and occupy the greatest proportion of the side walls. Each
of these ovens is sixteen feet wide and forty feet deep. Their floors
being level with the surface of the casting table, the plates of glass
may be deposited in them immediately after they are cast, with little
difficulty and without delay.
“When the melted glass in the cuvette is found to be in the exact
state that experience has pointed out as being most favourable for its
flowing readily and equably, this vessel is withdrawn from the furnace
by means of a crane, and is placed upon a low carriage, in order to
its removal to the casting table, which, as it is previously placed
contiguous to the annealing oven that is to be filled, may therefore
be at a considerable distance from the melting furnace. Measures are
then taken for cleaning the exterior of the crucible, and for carefully
removing with a broad copper sabre any scum that may have formed upon
the surface of the glass, as the mixture of any of these foreign
matters would infallibly spoil the beauty of the plate. These done,
the cuvette is wound up to a sufficient height by a crane; and then,
by means of another simple piece of mechanism, is swung over the upper
end of the casting table; and being thrown into an inclined position,
a torrent of melted glass is suddenly poured out on the surface of the
table, which must previously have been heated, and wiped perfectly
clean.
“The glass is prevented from running off the sides of the table by ribs
of metal, one of which is placed along the whole length of each side,
their depth being the exact measure which it is desired to give to the
thickness of the glass. A similar rib, attached to a cross piece, is
temporarily held, during the casting, at the lower end of the table.
When the whole contents of the crucible have been delivered, a large
hollow copper cylinder, which has been made perfectly true and smooth
in a turning lathe, and which extends entirely across the table,
resting on the side ribs, is set in motion; and the glass, during its
progress, is spread out into a sheet of uniform breadth and thickness.
Its length depends upon the quantity of melted glass contained in the
cuvette: should this be more than is needed for the formation of a
plate having the full dimensions of the table, the metal rib is removed
from its lower part, and the surplus glass is received in a vessel of
water placed under the extreme end for the purpose.
“Mr. Parkes, in speaking of this operation, remarks--‘The spectacle
of such a vast body of melted glass poured at once from an immense
crucible, on a metallic table of great magnitude, is truly grand; and
the variety of colours which the plate exhibits immediately after the
roller has passed over it, renders this an operation far more splendid
and interesting than can possibly be described.’
“At least twenty workmen are busily employed during this process of
casting. From the time that the cuvette is removed from the furnace,
to the completion of the casting by the hardening of the glass, the
apartment must be kept as free as possible from disturbance; even
the opening and shutting of a door might, by setting the air in
motion, disturb the surface of the glass, and thus impair the value
of the plate. So soon as it is completely set, the plate is carefully
inspected; and should any flaws or bubbles appear upon any part of its
surface, it is immediately divided by cutting through them.”
“When the plate of glass thus formed has been sufficiently fixed by
cooling, it is slipped from the table gradually and carefully into one
of the annealing ovens, where it remains in a horizontal position; its
treatment differing in this respect from that pursued with crown and
broad glass, which stand on edge during the annealing process. As each
oven in this manner becomes filled, it is closed up by an iron door,
the crevices of which are carefully stopped with mortar or clay, to
prevent an access of external air to the oven; and thus to provide as
far as possible for the gradual cooling of the plates, the necessity
for which has already been sufficiently explained. When the glass has
remained during about fifteen days in these ovens, they are opened, and
the contents withdrawn.”
The plates have then to undergo the operations of squaring, grinding,
and polishing, which need not be described in this place.
The various kinds of glass manufactured in Great Britain amount every
year to the enormous quantity of 300,000 cwt., which is valued at two
millions sterling.
Glass Cutting.
Such, then, being a few details as to the mode of manufacturing glass;
we will next suppose that the glass has reached the hands of the
glazier or glass-cutter; and that the window-frame or sashes are ready
to receive the panes of glass.
One of the earlier operations of the glazier is to _prime_ the sash,
that is, to give it a coat of thin paint, for the purpose of making the
putty adhere more firmly to the wood. He next takes the dimensions, in
inches and eighths of an inch, of the groove or rebate in which each
square of glass is to be fixed, and then proceeds to cut squares of
those sizes from the semicircular pieces in his crate. This requires
much tact and judgment, since to procure square or rectangular panes
necessarily entails a loss of some of the circular portions. The
circular sheets are made of diameters varying from forty-eight to
sixty-four inches, and these are cut at various distances from the
central knot, so that the glazier is enabled to choose that piece which
experience teaches him will entail least waste: sometimes it is better
to cut the pane from a _table_ (the half which contains the knot),
sometimes from a _slab_ (the remaining portion of the disc).
In order to cut a table or slab, so as to procure a pane of the proper
size, the straight edge of the table is placed near the glazier, and he
cuts at right angles to it, by means of a diamond, and of an instrument
called a _square_; and two other cuts, at the proper distances, are
sufficient to give a pane of the required size. With respect to the
power by which a diamond is enabled to cut glass, we may explain it by
saying, that it is a general rule among mineralogists, lapidaries, and
others concerned with stony or crystalline bodies, that the hardest
among a certain number of bodies will _cut_, or at least _scratch_,
any of the others:--in fact, tables of the _hardness_ of different
substances are formed from the determination of what substances will
mark or scratch others, that one being reckoned hardest which will
scratch all others, without being equally affected by them in return.
Now the diamond is the hardest body in nature, and cannot be cut by
any substance but its own dust; but it can cut glass and other bodies,
which are not so hard as itself.
The Process of Glazing.
The glass having been cut to the right size, it is next to be fitted
into the sash; and among the many kinds of cement which might be
suggested for this purpose, _oil putty_ is found to be the most
advantageous, since it is conveniently soft when used, but hardens
afterwards to the consistence of stone. Putty is made of whiting and
linseed oil. The whiting is purchased in lumps, which are well dried,
and then pounded and sifted. The linseed oil is poured into a tub, and
the powdered whiting added to it, and stirred up with a stick. When
some degree of stiffness is attained, the mass is taken out of the tub
and placed upon a board, where more whiting is added, and the whole
mixed up by hand. The mass is then beaten for a long time with a wooden
mallet, until it attains a perfectly smooth and uniform consistency.
A portion of putty is taken up on a knife, and inserted in the groove
of the window sash. The pane of glass is then laid in the groove, and
gently pressed down in every part, so as to lie on the putty. As the
sheets of glass are never perfectly flat, it is a rule among glaziers
to let the _concave_ side of a pane be within doors and the convex
side without. After the glass is laid in, the edge is carefully coated
with putty, to the extent of about an eighth of an inch: if this be
carefully done, it is sufficient to secure the glass in its place,
without presenting an unsightly appearance from the interior of a room.
The opposite side of the glass now requires a little attention, since
the bed of putty originally laid in the groove has been partially
squeezed out by the pane of glass: a little trimming and finishing are
all that are required in this matter.
When a broken pane is to be replaced in a window, it is done generally
without taking out the sash; but in the case of glazing the sashes of
a new house, such as we have been supposing, it is done before the
sashes are fitted into their places. If sashes are glazed with _plate_
instead of _crown_ glass, the only difference in the glazier’s method
of proceeding is, that the pane being heavier, must be fixed in with
greater attention to security. Sometimes a small beading or fillet of
wood is used instead of putty, in which case it is either nailed or
screwed to the sash.
Where skylights are used instead of windows, a different plan must
be observed, since there are no cross bars to the sashes. In this
case the squares of glass are fixed in somewhat in the way adopted in
slating a roof, that is, the lower pieces are puttied in first, and
the upper ones are lapped over them, so that each pane projects about
three-quarters of an inch over the one next below it. This is to effect
two objects,--to prevent the necessity of puttying the joints, and to
exclude rain.
_Ground_, _fluted_, _painted_, _stained_, and _embossed_ glass, are
occasionally employed for windows. These need not be noticed, since the
processes by which they are fluted, stained, &c., would carry us to
details of too extensive a nature. So far as the glazier is concerned,
rather more care and delicacy are required in proportion as the kind of
glass employed is more costly or more ornamental.
In some of the better kinds of houses, rooms are provided with double
windows, separated a few inches from one another. The object of this
is, to prevent the room from being affected by rigorous cold from
without; for a mass of air _when stationary_, conducts heat very
slowly; the stratum of air between the two windows, therefore,--being
stationary,--is slow to conduct the cold from without, or, more
correctly, to conduct the warmth from within.
Sheet Lead for Roofs and Cisterns.
Whether the glazier precedes the plumber or the plumber the glazier,
or whether the labours of both alternate during the building of a
house, is a question of no great importance to our present object. We
will therefore proceed to notice the kind of material employed by the
plumber.
The comparative cheapness of lead, its admirable qualities, and the
facility with which it can be cast and rolled into thin sheets, and
drawn into pipes, cause it to be extensively used in building. The
most productive mines of this metal in our own country are situated in
Derbyshire, Devonshire, Cornwall, in Wales, and in the North; in short,
the ore from which lead is generally obtained, called _Galena_, or
_Sulphuret of Lead_, is found in all countries where the primary rocks
appear at the surface. The ore greatly resembles the pure metal in
brilliancy; but it is brittle, and not so easily fused. It frequently
contains a sufficient quantity of silver to make it worth while to
adopt a peculiar process in the reduction of it, in order to separate
this more valuable metal. The ore is first broken into small pieces,
and is then _roasted_ in a reverberatory furnace, to drive off the
sulphur. When this object is attained, the heat is increased, till the
metal is fused, and then it is drawn off into moulds, which give it the
form of blocks or slabs, called _sows_ and _pigs_.
_Sheet lead_ is made thus:--A large furnace is provided, into which
pig-lead is thrown, and heat applied. When the lead is melted, a valve
or cock is opened in the side of the furnace, and the glistening liquid
metal pours forth, and falls on a large table, covered over with an
even surface of fine sand, and having a ledge of an equal height above
the sand all round it. When the melted metal is poured on the sand,
two men, holding each end of a stiff wooden rule, called a _strike_,
draw it along the table, resting on each side ledge: the liquid lead is
pushed onwards by the strike, till it covers the whole surface of an
even thickness, which of course is governed by the depth of the ledge
round the table.
_Milled sheet lead_ is formed by rolling a cast plate of the metal
between large iron rollers, turned by machinery. These rollers are set
closer and closer together, till the lead is reduced by rolling to the
requisite degree of thinness. By this process, the lead is rendered
more dense and more equally so, than it ever is by simply casting:
milled lead, consequently, is more durable than cast-lead.
It should be here noticed that lead, when it is used for roofing, or
for lining cisterns and gutters, is always laid on an even boarded
surface, and not on battens or laths, like slate and tiles.
Lead Pipes.
Lead pipe is either formed by bending thin sheet lead round a
cylindrical mould, and soldering the joint; or when the pipe is less
than four or five inches in diameter, it is formed by casting a thick
cylinder of lead with a small bore, and about five or six feet long. A
long smooth iron rod, a little larger than the bore of the cylinder,
is forced into this, and then the cylinder is gradually drawn through
a succession of circular holes, decreasing in diameter, in a steel
plate, by means of a powerful draw-mill, worked by a steam-engine. The
lead is by this process extended out over the iron rod, which preserves
the bore of the pipe of an equal diameter, and when the pipe is
sufficiently reduced in thickness, the rod, or _triblet_, is forcibly
drawn out, and the pipe left with a smooth bore, ready for use.
Attempts have been made to form lead pipes wholly by casting; an outer
mould and an inner core being so adjusted as to leave a space between
them, into which lead might be forced while in a melted state; but this
method has not been practically worked out to any great extent.
The Process of Plumbing.
When a roof is to be covered, or a cistern lined, with lead, the sheet
of the metal is unrolled on a level floor, and made free from creases
and undulations, by beating them down with a heavy wooden _flogger_,
formed like a roller with a flattened side, and a handle to it. The
plumber then draws on the lead the form into which it must be cut to
fit the surface it is intended to cover, and afterwards cuts through
the lines described with a strong sharp knife. The piece is then rolled
up again for facility of carriage, and raised by tackle into its
intended situation, it being placed there so that when again unrolled,
it may lie in the proper situation and position on the boarding. The
sheet is then again beat out flat as before.
The next sheet being put into its place, and so that the edges of
the two may overlap about one and a half or two inches, the workman
proceeds to make the joint, or to solder the two sheets together. The
first step for this purpose is to scrape the two edges or borders of
the sheets that are to come in contact quite clean and bright, with a
tool constructed for this purpose, consisting of a small triangular bit
of steel ground sharp at its edges, and fastened at right angles on
an iron socket, fixed in a handle. When these borders of the lead are
quite clean, they are painted over with black-lead paint, to prevent
their tarnishing, or _oxidising_ again, as the solder will only adhere
to a clean pure metallic surface. The paint also serves as a flux to
cause the solder and lead to melt together, and thus make a close joint.
The solder is melted in an iron ladle, on a rude temporary fire-place,
built as near the spot where the solder is wanted as possible. The
plumber having turned back the edge of the upper sheet at the joint,
an assistant carefully pours the solder on the lower edge. The workman
then spreads it evenly along the joint, by means of _soldering irons_,
which are irregularly-shaped iron bars, swelling at their ends
into rounded forms of different sizes and shapes, according to the
particular purpose for which they are intended. These irons are used in
a red-hot state in order to keep the solder melted.
As soon as the workman has spread the solder, he presses and hammers
down the upper edge upon the lower, and spreads the solder forced
out of the joint, along the seam. The outermost edge of the lead
covering is nailed down to the boarding or cistern-frame by nails,
with their heads leaded over to prevent the corrosion of the metal, by
the chemical or _voltaic_ action that takes place when two metals in
contact are exposed to moisture. The situation of the soldered joints
depends on the size and form of the surface to be covered over; and a
good workman considers well how he can cut out the lead so as to have
the fewest joints, and these in the most favourable situations. If he
has to line a cistern, he will cover the bottom in one piece, cutting
the lead large enough to admit of its turning up for an inch or two at
two of the sides, the joint consequently being made at these angles.
When a large roof, like that of a church, is covered with lead, this
is laid on in parallel bands as wide as the sheet will admit of, the
edge of one sheet being turned over a wooden roller or fillet, nailed
down on the boarding to receive it, while the edge of the next sheet
is turned over the former lead again; the double thickness being well
_flogged_ down to render the joint water-tight: and in this case no
solder is used.
The edges of lead gutters that turn up against the inside of the
parapet are either laid as flat against the brick-work as possible,
and secured so by iron _holdfasts_, so as to prevent rain from getting
in; or to effect the same object, they are in all the better kind of
buildings, turned into a joint, in the brick-work, between two courses.
When the plumber has to join two lengths of lead pipe into one, he
opens out the end of one length into a funnel-shaped aperture, by
gently driving a wooden cone into it, so as to avoid splitting the
pipe. The end of the other length is then scraped down a little by the
triangular tool before mentioned, not only to obtain a clean surface
for soldering, but to allow of the end fitting into the funnel-shaped
aperture alluded to. The two pipes being thus put together, the workman
holds a thick wadding of old woollen cloth, well greased, under the
joint, while a labourer gently pours melted solder over the joint,
which the plumber smoothes and shapes down by his soldering-iron and
the cloth into a regular smooth rounded swelling, all round the joint,
making this perfectly close and water-tight.
We observed in the chapter on “Roofs,” that within the last few
years, the metal zinc has been much used instead of lead for all
the purposes of the latter, and many others beside, for which the
admirable qualities of zinc particularly qualify it. This metal is
lighter than lead, and equally durable in the open air. It bears water
almost equally well; but it is not so flexible or manageable, being
neither so fusible nor malleable. Zinc only admits of being rolled or
hammered when it is heated to about two hundred and twenty degrees
of Fahrenheit. When cold it is too brittle to bear much bending;
nevertheless, pipes, gutters, cisterns, chimney-pots, &c., are made out
of sheet zinc; and roofs, &c. covered with it.
Solder or Cement for Metals.
The solder alluded to above, as being the means of joining two pieces
of sheet lead or of lead pipe, is an alloy of lead and tin, in the
proportion of two parts of the former to one of the latter. This mixed
metal is fusible at a lower temperature than either the tin or the lead
separately; and may therefore be applied in a melting state to tin or
lead, which still remains solid, even at the same temperature: this it
is which constitutes the principle of soldering. The solder is cast
into triangular bars, weighing from thirty to fifty pounds each.
There has, however, been a method recently introduced which seems
likely to effect considerable changes in the mode of joining pieces of
metal, whether for buildings or for other purposes; and we may here
give some account of it.
The great object of soldering is of course to form joints or seams in
pipes, and other articles, so perfectly, that they shall be subject to
no leakage or flaw. But this object is not easily obtained by the old
method of soldering; the chances of flaw are numerous, and have been
enumerated thus:--1st, the difference of expansion between the lead and
its alloys with tin, a difference which is particularly experienced
in very cold or very elevated temperatures; 2nd, the electro-chemical
actions which are developed under certain circumstances by the contact
of two different metallic substances;[5] 3rd, the very powerful
reaction which a number of chemical agents exert on alloys of lead and
tin, though not upon lead alone; 4th, the extreme fragility of these
alloys, which, particularly when heated, often break on the slightest
blow; 5th, the difficulty of making the solder adhere to the surface of
the lead;[6] 6th, the use of rosin, which frequently conceals fractures
for a time.
All of these objections are removed by a new method of soldering,
invented by M. E. Desbassays de Richemont, who has recently obtained,
at the National Exhibition of Arts at Paris, a gold medal for his
invention. The committee on whose recommendation the medal was awarded,
included some of the most distinguished chemists and men of science
in France; and in their report on the subject, they say:--“We consider
this invention of the highest importance; it is applicable to many
branches of industry, and will render great service to a large number
of manufactures. Its efficacy has not only been proved by experiment,
but is confirmed by the fact, that most of our eminent manufacturers
and tradesmen have taken out licences for the use of it.”
This invention (which is patented in France, Great Britain, and
Ireland) is called _autogenous soldering_, and consists of a method
of uniting two pieces of metal without the use of solder. The parts
to be joined are united by the fusion of the metal at the points or
lines of junction; so that the pieces when joined form one homogeneous
mass, no part of which can be distinguished from the rest. This result
is obtained by means of jets of flame, produced by the combustion of
hydrogen gas, mixed with atmospheric air; these jets are so ingeniously
managed, that they can be used and directed with as much, or even more
facility, than the common tools of the solderer.
The apparatus employed in this new process consists of a peculiarly
constructed vessel for producing hydrogen gas, to which vessel a
variety of tubes and jets can be attached, so as to meet the various
demands of the solderer.
A section of the gas-producer is shown in fig. 1: _a_ is a leaden tank,
for containing dilute sulphuric acid; _b_, a pipe which passes from the
acid vessel to another similar leaden vessel, _c_, which is to contain
cuttings of zinc; _d_ is a conical plug, with a stalk and handle
covered with lead, by the opening of which the acid is allowed to flow
through the pipe _b_, to the zinc cuttings, and thus hydrogen gas is
produced; _e_ is an opening by which zinc is put into the vessel _c_.
The opening, _e_, has a cover furnished with screws and nuts, by which
it may be firmly secured; _f_ is an opening by which acid and water are
poured into the vessel _a_. When the hydrogen gas is produced, it has
to pass through the safety chamber _g_; _h_ is a bent tube or pipe,
which conducts the gas from the vessel _c_ to the bottom of the safety
chamber, the mouth of the pipe dipping into an inch or two of water in
the safety chamber. This water is introduced by the pipe _i_, which is
furnished with a stopple. The cock, _k_, cuts off the flow of gas from
the vessel _c_, to the safety chamber, _g_. A flexible tube, _m_, is
screwed to the top of the safety chamber, and conveys the gas to the
working instrument, or jet, in the hands of the solderer.
As long as the dilute acid is allowed to flow upon the zinc, hydrogen
gas will be produced: the gas will also be formed as long as the
cock is open, which allows the gas to issue as it is produced; but
as soon as the cock is shut, a small quantity of gas accumulates,
and interferes with the further action of the liquid on the zinc.
Consequently there is no danger of an explosion, because the production
of the gas is never more than is required for working; and when the
work ceases, the production of the gas ceases also. When the dilute
acid has become saturated with oxide of zinc, and gas ceases to be
produced, the discharging pipe is opened, and the liquid withdrawn. By
spontaneous evaporation, this liquid furnishes sulphate of zinc (white
vitriol), which may be sold at a price which will more than cover the
first and daily cost of the apparatus.
[Illustration: Fig. 1.]
[Illustration: Fig. 2.]
We now proceed to describe the part of the apparatus with which the
workman operates. In fig. 2, the flexible tube, _m_, is attached to
one arm of the forked tube, _o_; the other arm of _o_ is attached to a
pipe, _q_, proceeding from a bellows, or other means for supplying air.
The solderer may work a bellows with his foot to supply his apparatus
with air, or the men in a whole factory may be supplied from a blowing
apparatus. A cock, _n_, regulates the supply of gas; _p_ is a cock for
regulating the supply of air; _r_ is the pipe or tube in which the gas
and air are mixed; _s_, the beak or tool, from which issues the jet of
flame, _t_, with which the workman operates.
The forked tube, _o_, is attached to the girdle of the workman, and the
regulating cocks, _n_ and _p_, are so placed, that by using one hand,
the man can allow the exact proportions of air and gas to issue. By
stopping both cocks, the flame is of course extinguished.
The beak, _s_, may be exchanged for others of every variety of form, so
as to produce jets of flame adapted to any kind of work. Fig. 3 is a
tool formed like the rosette of a watering-pot, capable of producing a
most intense flame of jets.
[Illustration: Fig. 3.]
[Illustration: Fig. 4.]
Fig. 4 allows a length of flame instead of a point to be produced; _n_
is the hydrogen gas-pipe and cock; _p_, the air-pipe and cock; _r_,
the tube, in which air and gas mingle; _u_, a pipe with a longitudinal
slit on one side of it; and _v_, another pipe covering _u_, and
exactly fitting over it. Gas and air escaping from the slit, on being
ignited, will produce a long strip of flame, which may be lengthened or
shortened by sliding off or on the covering tube, _v_, on the slit tube
_u_.
[Illustration: Fig. 5.]
Fig. 5 is a soldering tool, to be used where a jet of flame is not
available, as in joining zinc. In this arrangement, the hydrogen
and air flame heats apiece of copper, _y_, with which the work is
performed. _w_ is the tool, with a hollow handle and stalk; air being
supplied by the pipe _p_, passes through the hollow handle and stalk;
_x_ is a small tube which passes down the hollow handle and stalk,
_w_, and conveys gas from the pipe _n_ to the extremity of _w_, where
it mingles with the issuing air, and, on being ignited, the flame will
heat the piece of copper, _y_, (which, of course, may be of the shape
of any soldering tool required,) held by the arms, _z_.
Advantages of the Improved Method of Soldering Metals.
One great advantage to the public at large to be derived from the
general introduction of “autogenous soldering,” will be the diminution
of the number of cases of the escape of water and gas, which every day
occasion so much inconvenience and even danger as regards the stability
of buildings, the maintenance of the public thoroughfares, and the
security of life.
The disuse of charcoal and tin by plumbers will have the important
effect of rendering their trade less unhealthy, the fumes from their
brasiers, and the arsenical vapours emanating from impure tin, being a
very common cause of serious maladies.
By the old method of soldering, there is great danger of setting fire
to houses and public buildings: the destruction of the corn market of
Paris, and of the Cathedrals of Chartres and of Bruges, by fire, was
partly owing to the negligence of plumbers; a negligence for which
there could be no reason, if the new method of soldering had been
introduced, since it is only necessary to turn a cock in order to
extinguish or rekindle, at any moment, the jet of gas which serves for
the plumber’s tool. By means of the new apparatus, a soldering flame
can be conducted to a distance of several fathoms without the dangerous
necessity of lighting a brasier to heat irons, to melt masses of
solder, and to carry the whole into the midst of complicated carpentry
work.
The disuse of solder will also greatly reduce the price of plumber’s
work, without, however, diminishing the demand for the services of the
workmen. The disuse of seams or overlapping, which from this new mode
of connecting lengths of lead will almost entirely be given up, will
alone occasion a considerable saving in the quantity of lead employed.
The ease with which lead of from one-thirtieth to one-tenth of an inch
in thickness may be soldered, and defects repaired, will permit of
the substitution of this, in many cases, for thicker lead, and thus
diminish the expense; perhaps, also, it will give rise to the use of
lead for purposes to which it has not yet been applied, or the return
to others, in which from motives of economy it has been superseded by
other metals.
The plumber will also be indebted to M. de Richemont’s method for
several important improvements. He will be able in future to make
internal joints wherever a jet of flame can be introduced and directed;
to reconstruct on the spot, of pure lead, any portion of a pipe,
a vase, or a statue, that may have been removed or destroyed; to
execute in rapid succession any number of solderings; to repair in
a few minutes all dents, cracks, and flaws, in sheets or pipes of
new lead; to remove entirely the enormous edges or knots left by the
old-fashioned joints, and that without weakening them; to give, in
short, to works of lead a precision of execution, and a solidity,
unattainable up to this time.
Autogenous soldering will also be of great assistance to several
chemical manufactures, where it is so important to have large vessels
of lead without alloy. By uniting a number of sheets into one, vessels
of pure lead of any size may be formed for the process of acidification
and concentration of saline solutions; for the formation of scouring
vats employed by so many artisans who work metals; for vessels of every
kind used to contain liquids which act upon tin solder.
In the repair of leaden vessels exposed to the action of heat, peculiar
advantages are offered by autogenous soldering. By the old method, the
holes which are so often caused in the bottoms of these vessels, either
by the action of sudden flames, or by deposits that form on their
surface, can be stopped only when they are not of too large dimensions,
by making what are called weldings of pure lead. The cases in which
this mode of repair is available, are very limited, and whenever it is
impracticable, the boilers must be taken down, the lead changed, and
then reset; thus occasioning considerable expense and an interruption
to business. By the new method, nothing is easier than to apply pieces
to the bottom or sides of the vessels, whatever be the size of the
holes, and thus the whole of a boiler may be renewed piecemeal. By
this plan, too, the old lead remains uncontaminated with solder, and
consequently will yield a pure metal to the melting-pot.
The great ductility of lead, which, in many cases, is one of its most
valuable qualities, is, however, an inconvenience when instruments or
utensils are required of considerable strength. At the same time, there
are circumstances where this metal alone can be employed, on account
of the manner in which it resists chemical action. By constructing
vessels or instruments of iron, zinc, or wood, and covering them with
lead, utensils can be formed that will resist pressure and blows, and
most chemical agents, as well as if they were made of solid lead.
Such vessels are required in the preparation of soda, and other
gaseous waters; in the distillation or evaporation of acid or alkaline
solutions; and for many other purposes.
Another application that deserves especial notice is that of lining
common barrels with thin sheet-lead. These vessels would be of great
utility in chemical factories, more particularly in the construction of
Woulf’s apparatus, and other pneumatic instruments, to which greater
dimensions could be given by this means; but they could be employed
with singular advantage in the transport of acid and alkaline liquids
by sea and land. Sulphuric and muriatic acids are transported in stone
bottles, or glass carboys placed in baskets, which, however carefully
packed, are liable to be broken, not only with the loss of the acids,
but with danger to surrounding bodies. We are told of two French ships
that perished at sea on a voyage to the colonies, in consequence of the
breaking of some bottles of sulphuric acid.
In the manufacture of sulphuric acid, the use of ordinary solder is
impracticable, since it would soon be corroded. The following method
was introduced some years ago for forming sulphuric acid chambers, and
the concentration pans. Two edges of lead being placed in contact,
were flattened down into a long wooden groove, and secured in their
situation by a few brass pins driven into the wood. The surfaces
were next brightened by a triangular scraper, rubbed over with
candle-grease, and then covered with a stream of hot melted lead. The
riband of lead thus applied, was finally equalized by being brought
into partial fusion with the plumber’s conical iron, heated to redness;
the contact of air being prevented by sprinkling rosin over the
surface. The autogenous soldering apparatus will greatly simplify the
above method.
The advantages to be derived from the new process, are by no means
confined to lead: the apparatus may be employed in using for solder
either the common alloys, or pure lead, to unite zinc, and iron, and
lead, with iron, copper, and zinc. It may be substituted also with
advantage for the common blow-pipe and lamp of the enameller in all
their applications to the soldering and joining performed by the aid of
these instruments by jewellers, goldsmiths, tinmen, manufacturers of
plated goods, of buttons, &c.
The flame produced by the combustion of the gas may be most
economically employed for heating soldering irons. A few seconds
suffice to bring the iron to the desired temperature, and it can be
kept at that temperature for many hours without being liable to burn,
nothing more being necessary than to regulate the flame by means of
cocks, and the workman need not be obliged to change his iron, or even
to leave it for a single moment. Hence there is not only a considerable
saving in manual labour, but also in fuel, which in most cases is of
greater consequence.
Such are a few only of the advantages of this simple and beautiful
invention, which is now very extensively adopted in France, and will
doubtless get into extensive use in this country, when its merits are
more generally known.
It may be here stated, in justice to some of our own ingenious
countrymen, that after this method had become extensively known,
M. Richemont’s claim to the invention was disputed. We have been
informed, that previously to the year 1833, a Mr. Mallet had employed
an apparatus constructed on the same principle, and used in a similar
manner, as that already described as the invention of M. de Richemont.
In LOUDON’S _Encyclopædia of Cottage Architecture_, published in 1833,
the following passage occurs:--“Mr. Daniell, of King’s College, London,
has since published the same thing as new, and of his invention:
however, I can establish priority by my laboratory journal.”
FOOTNOTES:
[5] Messrs. Vauquelin and D’Arcet state that they have seen in
soap-works the soldering of vats lined with lead crumble in a few days
to a powder. The same has been remarked of leaden pipes passing through
certain soils.
[6] The solder often sticks without uniting and the workman may be
quite ignorant of his imperfect work; and thus gas, water, or dangerous
liquids, may be allowed to escape.