Читать книгу Henley's Formulas, Recipes and Processes (Applied Chemistry) - Various - Страница 222

—I. Copper oxide is reduced by means of hydrogen or copper sulphate by boiling a solution of the same in water with some zinc filings in order to obtain entirely pure copper. Of the copper powder obtained in this manner, 20, 30, or 36 parts, by weight, according to the degree of hardness desired for the composition (the greater the quantity of copper used the harder will the composition become), are thoroughly moistened in a cast-iron or porcelain mortar with sulphuric acid of 1.85 specific gravity; 70 parts, by weight, of mercury are then added to this paste, the whole being constantly stirred. When all the copper has been thoroughly amalgamated with the mercury, the sulphuric acid is washed out again with boiling water, and in 12 hours after it has become cold the composition will be so hard that it can be polished. It is impervious to the action of dilute acids, alcohol, ether, and boiling water. It contains the same specific gravity, alike in the soft or the hard condition. When used as a cement, it can at any time be rendered soft and plastic in the following manner: If applied while hot and plastic to the deoxidized surfaces of two pieces of metal, these latter will unite so firmly that in about 10 or 12 hours the metal may be subjected to any mechanical process. The properties of this composition render it very useful for various purposes, and it forms a most effective cement for fine metal articles which cannot be soldered in fire.

II.—Bismuth, 5.5 parts; lead, 3; tin, 1.5.

III. Alloy d’Homburg.—Bismuth, {66} 3 parts; lead, 3; tin, 3. This alloy is fusible at 251° F., and is of a silvery white. It is employed for reproductions of medals.

IV. Alloy Valentine Rose.—Bismuth, 4 to 6 parts; lead, 2 parts; tin, 2 to 3 parts. This alloy fuses at 212° to 250° F.

V. Alloy Rose père.—Bismuth, 2 parts; lead, 2; tin, 2. This alloy fuses at 199° F.

The remainder are plastic alloys for reproducing cuts, medals, coins, etc.:

VI.—Bismuth, 4 parts; lead, 2 parts; tin, 1 part.

VII.—Bismuth, 3 parts; lead, 3 parts; tin, 2 parts.

VIII.—Bismuth, 4 parts; lead, 2 parts; tin, 2 parts.

IX.—Bismuth, 5 parts; lead, 2 parts; tin, 3 parts.

X.—Bismuth, 2 parts; lead, 2 parts; tin, 2 parts.