7. (Sample made from the ore of Hilburghausen.) Copper, 401⁄2 parts; nickel, 311⁄2 parts; iron, 21⁄2 parts; zinc, 251⁄2 parts. Equal to the best Chinese sample.
8. (Pelouze.) Copper and nickel, equal parts. Recommended by M. Pelouze as superior to any of the alloys containing zinc.
9. (Pelouze.) Copper, 2 parts; nickel, 1 part. Not so white as the last, but more malleable.
10. (White Copper from China.)—a. Copper, 30 parts; nickel, 36 parts; zinc, 34 parts.
b. (Said to be prepared from native ore.) Copper, 41 parts; nickel, 32 parts; iron, 21⁄2 parts; zinc, 241⁄2 parts. Silvery white, takes a high polish, very sonorous, malleable both cold and at a dull-red heat, and may be rolled into leaves or formed into wire.
11. (White metal spoon, sold as ‘German Plate.’) Copper, 55 parts; nickel, 24 parts; zinc, 16 parts; tin, 3 parts; iron, 2 parts.
Anal. This may be briefly described as follows:—a. 100 gr. of the alloy is digested in nitric acid q. s., diluted with a little water. If the sample is unequally attacked by the acid, and a white external shell is observed which dissolves more slowly than the internal portion, it is ‘plated’ on those parts with silver. If this silver shell or casing has a polished surface on both sides, the article has been ‘electro-plated,’ if the contrary is the case, it has most probably been plated in the usual way.
b. The solution being completed, heat is applied to expel the excess of acid, and the remainder is largely diluted with distilled water; dilute hydrochloric acid is now dropped in as long as it occasions a precipitate, and the whole, after being moderately heated for a short time, and cooled, is thrown upon a small paper filter; the precipitate on the filter is next washed with distilled water, carefully dried, and ignited in a small porcelain crucible, the filter itself being separately burnt on the cover of the crucible, and the ashes added to its contents prior to ignition. Every 1431⁄2 gr. of the resulting fused chloride is equal to 108 gr. of metallic silver.
c. The filtered liquid (see b) is next treated
with a stream of sulphuretted hydrogen, and the black precipitate is collected, washed, and digested in strong nitric acid; when the solution is complete sulphuric acid is dropped in to precipitate the lead (if any is present); if a precipitate is formed, the whole is evaporated to dryness, and the excess of sulphuric acid expelled by a rather strong heat applied towards the end; the dry mass is now collected on a filter, washed with a mixture of water and alcohol, dried, and exposed to slight ignition in a porcelain crucible. Every 152 gr. of the resulting dry sulphate is equal to 104 gr. of lead.