dissolved, or at least softened, by petroleum. An alloy of lead 3
parts, tin 2, bismuth 2.5, melting at 212° F., is not affected by
petroleum, and is therefore very useful for cementing lamps made of
metal and glass combined.
LIPOWITZ’S BISMUTH ALLOY: See Cadmium Alloys.
«BRASS.»
In general brass is composed of two-thirds copper and one-third zinc,
but a little lead or tin is sometimes advantageous, as the following:
I.—Red copper, 66 parts; zinc, 34 parts; lead, 1 part.
II.—Copper, 66 parts; zinc, 32 parts; tin, 1 part; lead, 1 part.
III.—Copper, 64.5 parts; zinc, 33.5 parts; lead, 1.5 parts; tin, 0.5
part.
«Brass-Aluminum.»—A small addition of aluminum to brass (1.5 to 8
per cent) {53} greatly increases its hardness and elasticity, and
this alloy is also easily worked for any purpose. Brass containing 8
per cent of aluminum has the valuable property of being but slightly
affected by acids or gases. A larger percentage of aluminum makes the
brass brittle. It is to be noted that aluminum brass decreases very
materially in volume in casting, and the casts must be cooled slowly or
they will be brittle. It is an alloy easily made, and its low price,
combined with its excellent qualities, would seem to make it in many
cases an advantageous substitute for the expensive phosphorous bronze.
«Bristol Brass (Prince’s Metal).»—This alloy, which possesses
properties similar to those of French brass, is prepared in the
following proportions:
I II III
Copper 75.7 67.2 60.8
Zinc 24.3 32.8 39.2
Particular care is required to prevent the zinc from evaporating during
the fusing, and for this purpose it is customary to put only half of it
into the first melting, and to add the remainder when the first mass is
liquefied.
«Brass-Iron (Aich’s Metal).»—This is a variety of brass with an
admixture of iron, which gives it a considerable degree of tenacity.
It is especially adapted for purposes which require a hard and, at the
same time, tenacious metal. Analyses of the various kinds of this metal
show considerable variation in the proportions. Even the amount of
iron, to which the hardening effect must be attributed, may vary within
wide limits without materially modifying the tenacity which is the
essential characteristic of this alloy.
I.—The best variety of Aich’s metal consists of copper, 60 parts;
zinc, 38.2; iron, 1.8. The predominating quality of this alloy is its
hardness, which is claimed to be not inferior to that of certain kinds
of steel. It has a beautiful golden-yellow color, and is said not to
oxidize easily, a valuable property for articles exposed to the action
of air and water.
II.—Copper, 60.2 parts; zinc, 38.2; iron, 1.6. The permissible
variations in the content of iron are from 0.4 to 3 per cent.
Sterro metal may properly be considered in connection with Aich’s
metal, since its constituents are the same and its properties very
similar. The principal difference between the two metals is that sterro
metal contains a much larger amount of iron. The composition of this
alloy varies considerably with different manufacturers.
III.—Two varieties of excellent quality are the product of the Rosthorn
factory, in Lower Austria—copper, 55.33 parts; zinc, 41.80; iron, 4.66.
Also
IV.—English sterro metal (Gedge’s alloy for ship sheathing), copper, 60
parts; zinc, 38.125; iron, 1.5.
The great value of this alloy lies in its strength, which is equaled
only by that of the best steel. As an illustration of this, a
wrought-iron pipe broke with a pressure of 267 atmospheres, while a
similar pipe of sterro metal withstood the enormous pressure of 763
atmospheres without cracking. Besides its remarkable strength, it
possesses a high degree of elasticity, and is, therefore, particularly
suitable for purposes which require the combination of these two
qualities, such as the construction of hydraulic cylinders. It is well
known that these cylinders, at a certain pressure, begin to sweat, that
is, the interior pressure is so great that the water permeates through
the pores of the steel. With a sterro metal cylinder, the pressure can
be considerably increased without any moisture being perceptible on the
outside of the cylinder.
Sterro metal can be made even more hard and dense, if required
for special purposes, but this is effected rather by mechanical
manipulation than by any change in the chemical composition. If rolled
or hammered in heat, its strength is increased, and it acquires, in
addition, an exceedingly high degree of tenacity. Special care must be
taken, however, in hammering not to overheat the metal, as in this case
it would become brittle and might crack under the hammer. Sterro metal
is especially suitable for all the purposes for which the so-called red
metal has been in the past almost exclusively used. Axle bearings, for
example, made of sterro metal have such excellent qualities that many
machine factories are now using this material entirely for the purpose.
«Cast Brass.»—The various articles of bronze, so called, statuettes,
clock cases, etc., made in France, where this industry has attained
great perfection and extensive proportions, are not, in many cases,
genuine bronze, but fine cast brass. Following are the compositions of
a few mixtures of metals most frequently used by French manufacturers:
Copper Zinc Tin Lead
I 63.70 33.55 2.50 0.25
II 64.45 32.44 0.25 2.86
III 70.90 24.05 2.00 3.05
IV 72.43 22.75 1.87 2.95
{54}
Their special advantage is that they can be readily cast, worked with
file and chisel, and easily gilded.
«To Cast Yellow Brass.»—If good, clean, yellow brass sand castings
are desired, the brass should not contain over 30 per cent of zinc.
This will assure an alloy of good color and one which will run free
and clean. Tin or lead may be added without affecting the property of
casting clean. A mixture of 7 pounds of copper, 3 pounds of spelter, 4
ounces of tin, and 3 ounces of lead makes a good casting alloy and one
which will cut free and is strong. If a stronger alloy be desired, more
tin may be added, but 4 ounces is usually sufficient. If the alloy be
too hard, reduce the proportion of tin.
«Leaf Brass.»—This alloy is also called Dutch gold, or imitation gold
leaf. It is made of copper, 77.75 to 84.5 parts; zinc, 15.5 to 22.25.
Its color is pale or bright yellow or greenish, according to the
proportions of the metals. It has an unusual degree of ductility.
«Malleable Brass.»—This metal is affected less by sea water than
pure copper, and was formerly much used for ship sheathing, and for
making nails and rivets which were to come in contact with sea water.
At the present day it has lost much of its importance, since all the
larger ships are made of steel. It is usually composed of copper, 60
to 62 parts; and zinc, 40 to 38 parts. It is sometimes called yellow
metal, or Müntz metal (called after its inventor), and is prepared
with certain precautions, directed toward obtaining as fine a grain as
possible, experience having shown that only a fine-grained alloy of
uniform density can resist the action of the sea water evenly. A metal
of uneven density will wear in holes. To obtain as uniform a grain as
possible, small samples taken from the fused mass are cooled quickly
and examined as to fracture. If they do not show the desired uniform
grain, some zinc is added to the mass. After it has permeated the whole
mass, a fresh sample is taken and tested, this being continued until
the desired result is reached. It is scarcely necessary to remark that
considerable experience is required to tell the correct composition
of the alloy from the fracture. The mass is finally poured into molds
and rolled cold. Malleable brass can be worked warm, like iron, being
ductile in heat, a valuable quality.
Experiments with malleable brass show that all alloys containing up
to 58.33 per cent of copper and up to 41.67 per cent of zinc are
malleable. There is, in addition, a second group of such alloys, with
61.54 per cent of copper and 38.46 per cent of zinc, which are also
malleable in heat.
The preparation of these alloys requires considerable experience,
and is best accomplished by melting the metals together in the usual
manner, and heating the fused mass as strongly as possible. It must
be covered with a layer of charcoal dust to prevent oxidation of the
zinc. The mass becomes thinly fluid, and an intimate mixture of the
constituents is effected. Small pieces of the same alloy are thrown
into the liquid mass until it no longer shows a reflecting surface,
when it is cast into ingots in iron molds. The ingots are plunged
into water while still red-hot, and acquire by this treatment a very
high degree of ductility. The alloy, properly prepared, has a fibrous
fracture and a reddish-yellow color.
«Sheet Brass» (For Sheet and Wire).—In the preparation of brass for
the manufacture of wire, an especially pure quality of copper must be
used; without this, all efforts to produce a suitable quality of brass
will be in vain. That pure copper is indispensable to the manufacture
of good, ductile brass may be seen from the great difference in the
composition of the various kinds, all of which answer their purpose,
but contain widely varying quantities of copper and zinc. The following
table shows the composition of some excellent qualities of brass
suitable for making sheet and wire:
───────────────────+──────+──────+──────+─────
Brass Sheet—Source │Copper│ Zinc │ Lead │ Tin
───────────────────+──────+──────+──────+─────
Jemappes │ 64.6 │ 33.7 │ 1.4 │ 0.2
Stolberg │ 64.8 │ 32.8 │ 2.0 │ 0.4
Romilly │ 70.1 │ 29.26│ 0.38 │ 0.17
Rosthorn (Vienna) │ 68.1 │ 31.9 │ — │ —
Rosthorn (Vienna) │ 71.5 │ 28.5 │ — │ —
Rosthorn (Vienna) │ 71.1 │ 27.6 │ 1.3 │ —
Iserlohn & Romilly │ 70.1 │ 29.9 │ — │ —
Lüdenscheid │ 72.73│ 27.27│ — │ —
(Brittle) │ 63.66│ 33.02│ 2.52 │ —
Hegermühl │ 70.16│ 27.45│ 0.79 │ 0.20
Oker │ 68.98│ 29.54│ 0.97 │ —
│ │ │ │
Brass Wire— │ │ │ │
England │ 70.29│ 29.26│ 0.28 │ 0.17
Augsburg │ 71.89│ 27.63│ 0.85 │ —
Neustadt │ 70.16│ 27.45│ 0.2 │ 0.79
Neustadt │ 71.36│ 28.15│ — │ —
Neustadt │ 71.5 │ 28.5 │ — │ —
Neustadt │ 71.0 │ 27.6 │ — │ —
(Good quality) │ 65.4 │ 34.6 │ — │ —
(Brittle) │ 65.5 │ 32.4 │ 2.1 │ —
For wire and sheet │ 67.0 │ 32.0 │ 0.5 │ 0.5
───────────────────+──────+──────+──────+─────
{55}
As the above figures show, the percentage of zinc in the different
kinds of brass lies between 27 and 34. Recently, alloys containing a
somewhat larger quantity of zinc have been used, it having been found
that the toughness and ductility of the brass are increased thereby,
without injury to its tenacity. Alloys containing up to 37 per cent
of zinc possess a high degree of ductility in the cold, and are well
adapted for wire and sheet.
«Gilders’ Sheet Brass.»—Copper, 1 part; zinc, 1 part; tin, 1/10 part;
lead, 1/10 part. Very readily fusible and very dense.
«White Brass.»—Birmingham platina is an alloy of a pure white, almost
silver-white color, remaining unaffected by tolerably long exposure
to the atmosphere. Unfortunately this alloy is so brittle that it can
rarely be shaped except by casting. It is used only in the manufacture
of buttons. The alloy is poured into molds giving rather sharp
impressions and allowing the design on the button (letters or coat of
arms) to stand out prominently with careful stamping. The composition
of this alloy, also known by the name of platinum lead, is as follows:
I II
Copper 46.5 4
Zinc 53.5 16
III.—Zinc, 80 parts; copper, 10 parts; iron, 10 parts.
«BRITANNIA METAL.»
Britannia metal is an alloy consisting principally of tin and
antimony. Many varieties contain only these two metals, and may be
considered simply as tin hardened with antimony, while others contain,
in addition, certain quantities of copper, sometimes lead, and
occasionally, though rarely on account of its cost, bismuth. Britannia
metal is always of a silvery-white color, with a bluish tinge, and its
hardness makes it capable of taking a high polish, which is not lost
through exposure to the air. Ninety per cent of tin and 10 per cent
of antimony gives a composition which is the best for many purposes,
especially for casting, as it fills out the molds well, and is readily
fusible. In some cases, where articles made from it are to be subjected
to constant wear, a harder alloy is required. In the proportions given
above, the metal is indeed much harder than tin, but would still soon
give way under usage.
A table is appended, giving the composition of some of the varieties of
Britannia metal and their special names.
───────────────────────+─────+────────+──────+──────+────
│ Tin │Antimony│Copper│ Zinc │Lead
───────────────────────+─────+────────+──────+──────+────
English │81.90│ 16.25 │ 1.84 │ — │ —
English │90.62│ 7.81 │ 1.46 │ — │ —
English │90.1 │ 6.3 │ 3.1 │ 0.5 │ —
English │85.4 │ 9.66 │ 0.81 │ 3.06 │ —
Pewter │81.2 │ 5.7 │ 1.60 │ — │11.5
Pewter │89.3 │ 7.6 │ 1.8 │ — │ 1.8
Tutania │91.4 │ — │ 0.7 │ 0.3 │ 7.6
Queen’s metal │88.5 │ 7.1 │ 3.5 │ 0.9 │ —
German │72.0 │ 24.0 │ 4.0 │ — │ —
German │84.0 │ 9.0 │ 2.0 │ 5.0 │ —
German (for casting) │20.0 │ 64.0 │ 10.0 │ 6.0 │ —
Malleable (for casting)│48.0 │ — │ 3.0 │48.0 │ 1.0
───────────────────────+─────+────────+──────+──────+────
Britannia metal is prepared by melting the copper alone first, then
adding a part of the tin and the whole of the antimony. The heat can
then be quickly moderated, as the melting point of the new alloy is
much lower than that of copper. Finally, the rest of the tin is added,
and the mixture stirred constantly for some time to make it thoroughly
homogeneous.
An alloy which bears a resemblance to Britannia metal is Ashberry
metal, for which there are two formulas.
I II
Copper 2 3
Tin 8 79
Antimony 14 15
Zinc 1 2
Nickel 2 1
«BRONZES.»
The composition of bronze must be effected immediately before the
casting, for bronze cannot be kept in store ready prepared. In forming
the alloy, the refractory compound, copper, is first melted separately,
the other metals, tin, zinc, etc., previously heated, being then added;
the whole is then stirred and the casting carried out without loss of
time. The process of forming the alloy must be effected quickly, so
that there may be no loss of zinc, tin, or lead through oxidation,
and also no interruption to the flow of metal, as metal added after
an interval of time will not combine perfectly with the metal already
poured in. It is important, therefore, to ascertain the specific
weights of the metals, for the heavier metal will naturally tend to
sink to the bottom and the lighter to collect at the top. Only in this
way, and by vigorous stirring, can the complete blending of the two
metals be secured. In adding the zinc, great care {56} must be taken
that the latter sinks at once to the level of the copper, otherwise a
considerable portion will be volatilized before reaching the copper.
When the castings are made, they must be cooled as quickly as possible,
for the components of bronze have a tendency to form separate alloys of
various composition, thus producing the so-called tin spots. This is
much more likely to occur with a slow than with a sudden cooling of the
mass.
«Annealing Bronze.»—This process is more particularly employed in
the preparation of alloys used in the manufacture of cymbals, gongs,
bells, etc. The alloy is naturally brittle, and acquires the properties
essential to the purpose for which it is intended only after casting.
The instruments are plunged into cold water while red-hot, hammered,
reheated, and slowly cooled, when they become soft and sonorous. The
alloy of copper and tin has the peculiar property that, whereas steel
becomes hard through cooling, this mixture, when cooled suddenly,
becomes noticeably soft and more malleable. The alloy is heated to a
dark-red heat, or, in the case of thin articles, to the melting point
of lead, and then plunged in cold water. The alloy may be hammered
without splitting or breaking.
«Aluminum Bronze.»—This is prepared by melting the finest copper in a
crucible, and adding the aluminum. The copper is cooled thereby to the
thickly fluid point, but at the moment of the combination of the two
metals, so much heat is released that the alloy becomes white hot and
thinly fluid. Aluminum bronze thus prepared is usually brittle, and
acquires its best qualities only after having been remelted several
times. It may be remarked that, in order to obtain a bronze of the best
quality, only the very purest copper must be used; with an inferior
quality of copper, all labor is wasted. Aluminum bronze is not affected
by exposure to the air; and its beautiful color makes it very suitable
for manufacturing various ornamental articles, including clock cases,
door knobs, etc.
Aluminum bronze wire is almost as strong as good steel wire, and
castings made from it are almost as hard as steely iron; its resistance
to bending or sagging is great.
I.—A good formula is 90 to 95 per cent of aluminum and 5 to 10 per
cent of copper, of golden color, which keeps well in the air, without
soon becoming dull and changing color like pure copper and its alloys
with tin and zinc (bronze, brass, etc.). It can be cast excellently,
can be filed well and turned, possesses an extraordinary hardness and
firmness, and attains a high degree of polish; it is malleable and
forgeable. On the latter quality are founded applications which were
formerly never thought of, viz.: forged works of art for decorative
purposes. An alloy of 95 parts aluminum and 5 parts copper is used
here. The technical working of bronze is not materially different from
that of iron. The metal, especially in a hot condition, is worked like
iron on the anvil, with hammer and chisel, only that the temperature
to be maintained in forging lies between dark and light cherry red.
If the articles are not forged in one piece and the putting together
of the separate parts becomes necessary, riveting or soldering has to
be resorted to. Besides forging, aluminum bronze is well suited for
embossing, which is not surprising considering the high percentage of
copper. After finishing the pieces, the metal can be toned in manifold
ways by treatment with acid.
II.—Copper, 89 to 98 per cent; aluminum and nickel, 1 to 2 per cent.
Aluminum and nickel change in the opposite way, that is to say, in
increasing the percentage of nickel the amount of aluminum is decreased
by the equal quantity. It should be borne in mind that the best ratio
is aluminum, 9.5 per cent; nickel, 1 to 1.5 per cent at most. In
preparing the alloy a deoxidizing agent is added, viz., phosphorus to
0.5 per cent; magnesium to 1.5 per cent. The phosphorus should always
be added in the form of phosphorous copper or phosphor aluminum of
exactly determined percentage. It is first added to the copper, then
the aluminum and the nickel, and finally the magnesium, the last named
at the moment of liquidity, are admixed.
III.—A gold bronze, containing 3 to 5 per cent aluminum; specific
gravity, 8.37 to 8.15. Handsome golden color. This alloy oxidizes less
on heating than copper and iron, and is therefore especially adapted
for locomotive fireboxes and spindles, etc.
IV.—A steel bronze containing on an average 8.5 per cent aluminum
(including 1 per cent silicium); specific gravity, 7.7. Very ductile
and tough, but slightly elastic; hence its use is excluded where, with
large demands upon tension and pressure, no permanent change of form
must ensue. This is changed by working, such as rolling, drawing,
etc. {57} Especially useful where infrangibility is desired, as in
machinery, ordnance, etc. At high temperature this bronze loses its
elasticity again.
V.—This contains 8.5 per cent aluminum and 1 1/2 to 2 per cent
silicium. Its use is advisable in cases where the metal is to possess a
good elasticity, even in the cast state, and to retain it after being
worked in red heat.
VI.—An acid bronze, containing 10 per cent aluminum; specific gravity,
7.65. Especially serviceable to resist oxidation and the action of
acids.
VII.—Diamond bronze, containing 10 per cent aluminum and 2 per cent
silicium. Specific gravity, 7.3. Very hard; of great firmness, but
brittle.
«Art Bronzes.» (See also Aluminum Bronzes and Japanese Bronzes under
this title.)—I.—Copper, 84 parts; zinc, 11 parts; tin, 5 parts.
II.—Copper, 90 parts; zinc, 6 parts; tin, 2 parts; lead, 2 parts.
III.—Copper, 65 parts; zinc, 30 parts; tin, 5 parts.
IV.—Copper, 90 parts; tin, 5 parts; zinc, 4 parts; lead, 1 part.
V.—Copper, 85 parts; zinc, 10 parts; tin, 3 parts; lead, 2 parts.
VI.—Copper, 72 parts; zinc, 23 parts; tin, 3 parts; lead, 2 parts.
«Statuary Bronze.»—Many of the antique statues were made of genuine
bronze, which has advantages for this purpose, but has been superseded
in modern times by mixtures of metals containing, besides copper and
tin—the constituents of real bronze—a quantity of zinc, the alloy thus
formed being really an intermediate product between bronze and brass.
The reason for the use of such mixtures lies partly in the comparative
cheapness of their production as compared with genuine bronze, and
partly in the purpose for which the metal is to be used. A thoroughly
good statuary bronze must become thinly fluid in fusing, fill the molds
out sharply, allow of being easily worked with the file, and must take
on the beautiful green coating called patina, after being exposed to
the air for a short time.
Genuine bronze, however strongly heated, does not become thin enough to
fill out the molds well, and it is also difficult to obtain homogeneous
castings from it. Brass alone is also too thickly fluid, and not hard
enough for the required fine chiseling or chasing of the finished
object. Alloys containing zinc and tin, in addition to copper, can be
prepared in such a manner that they will become very thinly fluid, and
will give fine castings which can easily be worked with the file and
chisel. The best proportions seem to be from 10 to 18 per cent of zinc
and from 2 to 4 per cent of tin. In point of hardness, statuary bronze
holds an intermediate position between genuine bronze and brass, being
harder and tougher than the latter, but not so much so as the former.
Since statuary bronze is used principally for artistic purposes, much
depends upon the color. This can be varied from pale yellow to orange
yellow by slightly varying the content of tin or zinc, which must, of
course, still be kept between the limits given above. Too much tin
makes the alloy brittle and difficult to chisel; with too much zinc, on
the other hand, the warm tone of color is lost, and the bronze does not
acquire a fine patina.
The best proportions for statuary bronze are very definitely known at
the present day; yet it sometimes happens that large castings have not
the right character. They are either defective in color, or they do not
take on a fine patina, or they are difficult to chisel. These phenomena
may be due to the use of impure metals—containing oxides, iron, lead,
etc.—or to improper treatment of the alloy in melting. With the most
careful work possible, there is a considerable loss in melting—3 per
cent at the very least, and sometimes as much as 10. This is due to the
large proportion of zinc, and it is evident that, in consequence of it,
the nature of the alloy will be different from what might be expected
from the quantities of metals used in its manufacture.
It has been remarked that slight variations in composition quickly
change the color of the alloy. The following table gives a series of
alloys of different colors, suitable for statuary bronze: