With regard to malleability, as proved by rolling, the following order was observed, the numbers given being in the order of their capability of being rolled: Nos. IV, III, VI, II, I, V, VII, VIII, IX, X, XI, XII. No. IV not only rolled the best, without cracking on the edges, but was also the whitest in colour. All the ingots were numbered, and passed in succession through the rolls, the ingots being of the same thickness at the commencement. The condition of each was noticed after each squeeze of the rolls, and the thickness accurately measured. They were all likewise annealed together under the same conditions. The first six in order that is, Nos. IV, III, VI, II, I, V-rolled well, Nos. I and V being equal in this respect. Nos. VII and VIII rolled moderately well; and Nos. IX to XII rolled badly, the strips splitting down the middle long before they were reduced to the requisite thinness. For the above rolling tests the author is indebted to Mr. Wilcox of Messrs. Kemp and Co., Birmingham. The above results may be summarised as follows:-That 30 to 31 per cent of zinc, with less than double the amount of copper, gives the best results with respect to malleability and whiteness; 32 per cent of zinc makes the alloy more brittle and requires more frequent annealing during the rolling process; 1 to 2 per cent of iron may be present without seriously impairing the malleability, the alloys being whiter and harder; tin is very injurious, and imparts a yellowish tint to the alloy, even 2 per cent making the alloys unworkable.

No. V was the whitest and behaved itself irreproachably during rolling. Nos. III and IV were about equal in malleability, rolled better than No. II, and were whiter in colour. No. I was the worst of the series, both as regards colour and malleability. Any higher proportion of zinc, with 16 per cent of nickel, would probably be injurious. It is here noticeable that the best results were obtained with 30 per cent zinc, as in the 12 per cent nickel alloys, but with a less percentage of copper.

ALLOYS CONTAINING 20 PER CENT NICKEL

No. I rolled badly, but the casting was not sound, through being poured too hot, which somewhat impaired its malleability. No. III rolled well, although slightly cracked on the edges. No. IV rolled remarkably well with a clear feather edge. No. V was about equal to No. III, but whiter in colour. From these experiments it appears that 30 per cent zinc with 20 per cent nickel is rather too much; probably 28 per cent would combine the advantages of whiteness and malleability in the highest degree.

§ 92. The following analyses by the author of different articles made of German silver, by different makers, may be instructive :

The above were three different qualities made by the same firm. No. I had been boiled white in a tinning solution, and the tin was polished off before analysis.

The above were various qualities manufactured by another firm. No. VI was found to work very badly, probably due to iron, which is more injurious as the percentage of nickel is greater.

The following table gives the composition by analysis of German silver from various sources :-

The alloys in the preceding table containing lead are used for casting only, that metal making the alloy more fusible.

MANUFACTURE OF GERMAN SILVER

§ 93. The manufacture of German silver was formerly conducted in two distinct ways, known respectively as the German and English methods.

German Process.-In the German method the zinc and nickel to be used for a certain quantity of copper are divided into three equal portions. On the bottom of a graphite crucible, capable of holding 22 lbs. of the alloy, is placed a layer of copper, and upon this a layer of zinc and nickel ; upon this another layer of copper is placed, and so on until all the copper is in the crucible. One-third each of zinc

and nickel is retained for future addition. The contents of the crucible are then covered with charcoal powder, and the metals melted in an ordinary casting-furnace. When the contents are supposed to be liquefied, an iron rod is inserted, and if the whole is thoroughly fused, it is then vigorously stirred. The remaining zinc and nickel are then added in portions at a time, and the whole well stirred after each addition, a brisk fire being maintained to prevent chilling of the alloy by the freshly added metals. After the introduction of the last portion, an additional piece of zinc is thrown into the crucible to compensate for loss of zinc by volatilisation. If the alloy is intended for rolling, it is recommended to keep the finished alloy liquid for some time longer before casting, keeping the surface well covered with charcoal in the meantime.

English Process.—The English differs from the German method chiefly in the manner in which the metals are melted together, no portion of the zinc and nickel being retained, but the entire quantity of metals consisting of 81 lbs. copper, lb. zinc, and 2 to 3 lbs. nickel is melted at one time. The mixed metals are placed in a red-hot crucible and quickly covered with a thick layer of coal-dust. The furnace is urged to its highest pitch, so as to fuse the metals as quickly as possible. After ascertaining by an iron rod that the mass is liquefied, a previously prepared alloy, of 1 part by weight of zinc and part by weight of copper, is added, the quantity for the above charge varying between 1 and 2 lbs. When this alloy is melted, and the entire contents of the crucible forms a homogeneous whole, 2 lbs. of zinc are finally added. The mass, being