United States Government Gum. Dissolve 1 part of gum arabic in water and add 4 parts of sugar[p. 164] and 1 part of starch. This is then boiled for a few minutes, and thinned down as required.
To Make Different Alloys.—Silver-aluminum. Silver one-fourth part, and aluminum three-fourth parts.
Bell-metal. Copper, 80 parts; tin, 20 parts. Or, copper, 72 parts; tin, 26 parts; zinc, 2 parts. Or, copper 2; 1 of tin.
Brass. Copper, 66 parts; zinc, 32 parts; tin, 1 part; lead, 1 part.
Bronzes. Copper, 65 parts; zinc, 30 parts; tin, 5 parts. Or, copper, 85 parts; zinc, 10 parts; tin, 3 parts; lead, 2 parts.
German Silver. 52 parts of copper; 26 parts zinc; 22 parts nickel.
For Coating Mirrors. Tin, 70 parts; mercury, 30 parts.
Boiler Compounds.—To prevent scaling. Use common washing soda, or Glauber salts.
To Dissolve Celluloid.—Use 50 parts of alcohol and 5 parts of camphor for every 5 parts of celluloid. When the celluloid is put into the solution it will dissolve it.
To Soften Celluloid. This may be done by simply heating, so it will bend, and by putting it in steam, it can be worked like dough.