Part 39

Copper 88.8 93.6 Zinc 11.2 6.4

Copper 2.1 1.28 Zinc — 0.7 Brass 1.0 0.7

«Palladium Gold.»—Alloys of gold, copper, silver, and palladium have a brownish-red color and are nearly as hard as iron. They are sometimes (although rarely) used for the bearings for the axles of the wheels of fine watches, as they invite little friction and do not rust in the air. The composition used in the Swiss and English watch factories consists usually of gold 18 parts, copper 13 parts, silver 11, and palladium 6.

«Talmi Gold.»—The name of talmi gold was first applied to articles of jewelry, chains, earrings, bracelets, etc., brought from Paris, and distinguished by beautiful workmanship, a low price, and great durability. Later, when this alloy had acquired a considerable reputation, articles were introduced under the same name, but which were really made of other metals, and which retained their beautiful gold color only as long as they were not used. The fine varieties of talmi gold are manufactured from brass, copper, or tombac, covered with a thin plate of gold, combined with the base by rolling, under strong pressure. The plates are then rolled out by passing through rollers, and the coating not only acquires considerable density, but adheres so closely to the base that the metal will keep its beautiful appearance for years. Of late, many articles of talmi gold have been introduced whose gold coating is produced by electroplating, and is in many cases so thin that hard rubbing will bring through the color of the base. Such articles, of course, are not durable. In genuine talmi gold, the coating, even though it may be thin, adheres very closely to the base, for the reason that the two metals are actually welded by the rolling, and also because alloyed gold is always used, which is much harder than pure gold. The pure gold of electroplating is very soft. The composition of some varieties of talmi gold are here given. It will be seen that the content of gold varies greatly, and the durability of the alloy will, of course, correspond to this. The alloys I, II, III are genuine Paris talmi gold; IV, V, and VI are electroplated imitations; and VII is an alloy of a wrong composition, to which the gold does not adhere firmly:

Copper Zinc Tin Iron Gold I. 89.9 9.3 — — 1.3

II. 90.8 8.3 — — 0.9

III. 90.0 8.9 — — 0.9

IV. 90.7 89.0 — — 0.5 88.2 11.4

V. 87.5 12.4 — — 0.3 83.1 17.0

VI. 93.5 6.6 — — 0.05 84.5 15.8

VII. 86.0 12.0 1.1 0.3 —

«Japanese Alloys.»—In Japan some specialties in metallic alloys are in use of which the composition is as follows:

Shadke consists of copper with from 1 to 10 per cent of gold. Articles made from this alloy are laid in a pickle of blue vitriol, alum, and verdigris, until they acquire a bluish-black color.

Gui-shi-bu-ichi is an alloy of copper containing 30 to 50 per cent of silver. It possesses a peculiar gray shade.

Mokume consists of several compositions. Thus, about 30 gold foils (genuine) are welded together with shadke, copper, silver, and gui-shi-bu-ichi and pierced. The pierced holes are, after firmly hammering together the plates, filled up with the above-named pickle.

The finest Japanese brass consists of 10 parts copper and 8 parts zinc, and is called siachu. The bell metal kara kane is composed of copper 10 parts, tin 10 parts, iron 0.5 part, and zinc 1.5 parts. The copper is first fused, then the remaining metals are added in rotation.

«GERMAN SILVER OR ARGENTAN.»

The composition of this alloy varies considerably, but from the adjoined figures an average may be found, which will represent, approximately, the normal composition:

Copper 50 to 66 parts Zinc 19 to 31 parts Nickel 13 to 18 parts

The properties of the different kinds, such as their color, ductility, fusibility, {70} etc., vary with the proportions of the single metals. For making spoons, forks, cups, candlesticks, etc., the most suitable proportions are 50 parts of copper, 25 of zinc, and 25 of nickel. This metal has a beautiful blue-white color, and does not tarnish easily.

German silver is sometimes so brittle that a spoon, if allowed to fall upon the floor, will break; this, of course, indicates faulty composition. But the following table will show how the character of the alloy changes with the varying percentage of the metals composing it:

Copper Zinc Nickel Quality I. 8 3.5 4 Finest quality. II. 8 3.5 6 Beautiful, but refractory. III. 8 6.5 3 Ordinary, readily fusible. IV. 52 26.0 22 First quality. V. 59 30.0 11 Second quality. VI. 63 31.0 6 Third quality.

The following analyses give further particulars in regard to different kinds of German silver:

───────────+──────+──────+──────+─────+────── For sheet │Copper│ Zinc │Nickel│ Lead│ Iron ───────────+──────+──────+──────+─────+────── (French) │ 50.0 │ 31.3 │ 18.7 │ — │ — (French) │ 50.0 │ 30.0 │ 20.0 │ — │ — (French) │ 58.3 │ 25.0 │ 16.7 │ — │ — Vienna │ 50.0 │ 25.0 │ 25.0 │ — │ — Vienna │ 55.6 │ 22.0 │ 22.0 │ — │ — Vienna │ 60.0 │ 20.0 │ 20.0 │ — │ — Berlin │ 54.0 │ 28.0 │ 18.0 │ — │ — Berlin │ 55.5 │ 29.1 │ 17.5 │ — │ — English │ 63.34│ 17.01│ 19.13│ — │ — English │ 62.40│ 22.15│ 15.05│ — │ — English │ 62.63│ 26.05│ 10.85│ — │ — English │ 57.40│ 25. │ 13.0 │ — │ 3.0 Chinese │ 26.3 │ 36.8 │ 36.8 │ — │ — Chinese │ 43.8 │ 40.6 │ 15.6 │ — │ — Chinese │ 45.7 │ 36.9 │ 17.9 │ — │ — Chinese │ 40.4 │ 25.4 │ 31.6 │ — │ 2.6 Castings │ 48.5 │ 24.3 │ 24.3 │ 2.9 │ — Castings │ 54.5 │ 21.8 │ 21.8 │ 1.9 │ — Castings │ 58.3 │ 19.4 │ 19.4 │ 2.9 │ — Castings │ 57.8 │ 27.1 │ 14.3 │ 0.8 │ — Castings │ 57. │ 20.0 │ 20.0 │ 3.0 │ — ───────────+──────+──────+──────+─────+──────

In some kinds of German silver are found varying quantities of iron, manganese, tin, and very frequently lead, added for the purpose of changing the properties of the alloy or cheapening the cost of production. But all these metals have a detrimental rather than a beneficial effect upon the general character of the alloy, and especially lessen its power of resistance to the action of dilute acids, one of its most valuable properties. Lead makes it more fusible; tin acts somewhat as in bronze, making it denser and more resonant, and enabling it to take a higher polish. With iron or manganese the alloy is whiter, but it becomes at the same time more refractory and its tendency toward brittleness is increased.

«SUBSTITUTES FOR GERMAN SILVER.»

There are many formulas for alloys which claim to be substitutes for German silver; but no one of them has yet become an article of general commerce. It will be sufficient to note these materials briefly, giving the composition of the most important.

«Nickel Bronze.»—This is prepared by fusing together very highly purified nickel (99.5 per cent) with copper, tin, and zinc. A bronze is produced containing 20 per cent of nickel, light-colored and very hard.