A Silver Solder.
To make silver solder melt together 34 parts, by weight, silver coin, and five parts copper; after cooling a little, drop into the mixture 4 parts zinc, then heat again.
An Alloy For Glass Or Metal.
The following alloy, it is said, will attach itself firmly to glass, porcelain or metal.—Twenty to thirty parts of finely pulverulent copper, prepared by precipitation or reduction with the battery, are made into a paste with oil of vitriol. To this seventy parts of mercury are added, and well triturated. The acid is then washed out with boiling water and the compound allowed to cool. In ten or twelve hours it becomes sufficiently hard to receive a brilliant polish, and to scratch the surface of tin or gold. When heated it is plastic, but does not contract on cooling.
An Improved Process of Photo-Engraving.
The metal plate, of copper or zinc, is coated with a very thin layer of bitumen of Judæa, and when this coat has become perfectly dry, a film of bichromatized albumen is flowed over the plate. It is next exposed in the camera, and afterwards washed with water, in order to dissolve all the albumen which has not been rendered insoluble by the luminous action; it is then treated with spirit of turpentine, which dissolves all those parts of the layer of bitumen that have become exposed. The plate can now be attacked directly by water acidulated with from four to six per cent of nitric acid. The great advantage of this method consists in the high sensitiveness of the bichromatized albumen, at the same time preserving the solid reserve produced by the bitumen of Judæa on a metallic surface.
To Make New a Corroded Pen.
When a pen has become so corroded as to be useless, it can be made good as new by holding it in the flame of a gas jet for half a minute; then drop in cold water, take out, wipe clean, and it will be ready for use again.
Enamel for Fine Cards.
For the brilliant enamel now often generally applied to fine cards and other purposes, the following formula is given:—For white and for all pale and delicate shades, take twenty-four parts, by weight, of paraffine; add thereto 100 parts of pure kaolin (China clay), very dry and reduced to a fine powder. Before mixing with the kaolin, the paraffine must be heated to fusing point. Let the mixture cool, and it will form a homogeneous mass, which is to be reduced to powder, and worked into paste in a paint-mill, with warm water. This is the enamel ready for application. It can be tinted according to fancy.