Chapter I: II III

Silver 33 40 20 Copper 37–42 30–40 45–55 Nickel 25–30 20–30 25–35

The whitening of alloys of silver and copper is best accomplished by annealing the alloy until it turns black on the surface. Cool in a mixture of 20 parts, by weight, of concentrated sulphuric acid to 1,000 parts of distilled water and leave therein for some time. In place of the sulphuric acid, 40 parts of potassium bisulphate may be used per 1,000 parts of liquid. Repeat the process if necessary.

«Copper, Silver, and Cadmium Alloys.»—Cadmium added to silver alloys gives great flexibility and ductility, without affecting the white color; these properties are valuable in the manufacture of silver-plated ware and wire. The proportions of the metals vary in these alloys. Some of the most important varieties are given below.

Silver Copper Cadmium
I. 980 15 5
II. 950 15 35
III. 900 18 82
IV. 860 20 180
V. 666 25 309
VI. 667 50 284
VII. 500 50 450

In preparing these alloys, the great volatility of cadmium must be taken into account. It is customary to prepare first the alloy of silver and copper, and add the cadmium, which, as in the case of the alloys of silver and zinc, must be wrapped in paper. After putting it in, the mass is quickly stirred, and the alloy poured immediately into the molds. This is the surest way to prevent the volatilization of the cadmium.

«Silver, Copper, Nickel, and Zinc Alloys.»—These alloys, from the metals contained in them, may be characterized as argentan or German silver with a certain percentage of silver. They have been used for making small coins, as in the older coins of Switzerland. Being quite hard, they have the advantage of wearing well, but soon lose their beautiful white color and take on a disagreeable shade of yellow, like poor brass. The silver contained in them can be regained only by a laborious process, which is a great drawback to their use in coinage. The composition of the Swiss fractional coins is as follows:

20 centimes 10 centimes 5 centimes Silver 15 10 5 Copper 50 55 60 Nickel 25 25 25 Zinc 10 10 10

«Mousset’s Alloy.»—Copper, 59.06; silver, 27.56; zinc, 9.57; nickel, 3.42. This alloy is yellowish with a reddish tinge, but white on the fractured surface. It ranks next after Argent-Ruolz, which also contains sometimes certain quantities of zinc, and in this case may be classed together with the alloy just described. The following alloys can be rolled into sheet or drawn into wire: