A soap for metal work is as follows: The basis is cocoanut oil. Its ingredients are cocoanut oil, 2.5 kilos; chalk, 180 grins.; and alum, cream of tartar and white lead, of each 87.5 grins. The oil is melted in an iron vessel containing a little water, and the other ingredients are added in the order named, while constantly stirring the mixture. The mixture is then decanted into molds, wherein it solidifies. In use it is made into a paste with water and applied either by cotton waste or a rag. It is said this preparation never spoils in keeping.
To soften cast-iron, steep in 1 part of aqua fortis to 4 parts of water, and let it remain in twenty-four hours.
To soften rubber: If the rubber is unvulcanized, naphtha, bisulphide of carbon, and a variety of solvents may be employed, or slight heating will make a soft dough of it. If the rubber be vulcanized soft (like the rubber parts of boots and shoes), it cannot be softened without injury to it. Animal oils will do the softening in this case, but destroy the rubber instantly. If the rubber be hard (like penholders, buttons, etc.), it may be softened by heat and its shape changed by pressing. Rubber may be melted, but in every case it is ruined by such treatment, the result being a tar-like fluid that never again regains its original condition.
For softening steel so that it can be engraved and otherwise worked similarly to copper, pulverize beef bones and mix them with equal parts of calves' hair and loam and stir the mixture into a thick paste with water. A coat of this is applied to the steel and placed in a crucible. This is covered with another; the two are fastened with wire together, and the joint is closed hermetically with clay. The crucible is then placed in the fire and heated slowly. When through heating, it is cooled by being placed in the ashes.
To solder galvanized iron, also to solder tin to any iron: Muriatic acid reduced with zinc is used in soldering iron and tin, but it should be wiped off at once. It is used raw or unreduced in soldering galvanized iron.
An Argentan solder, which is readily adapted for use in iron and steel is composed of:
12 parts Nickel, 38 parts Copper, 50 parts Zinc.
Another Argentan solder which fuses readily is composed of:
8 parts Nickel, 35 parts Copper, 57 parts Zinc.
Bismuth solder is composed of the following:
(1) Lead, 4 parts; tin, 4 parts; bismuth, 1 part.
(2) Lead, 3 parts; tin, 3 parts; bismuth, 1 part.
(3) Lead, 2 parts; tin, 2 parts; bismuth, 1 part.
(4) Lead, 2 parts; tin, 1 part; bismuth, 2 parts.
(5) Lead, 3 parts; tin, 5 parts; bismuth, 3 parts.
(6) Bismuth solder is made of 1 part lead and 1 part tin and 1 part bismuth, which melts at 284 degrees Fahrenheit.