Frost Bites. Carbolized water, 4 drachms; nitric acid, 1 drop; oil of geranium, 1 drop.
Glass.—To cut glass, hold it under water, and use a pair of shears.
To make a hole through glass, place a circle of moist earth on the glass, and form a hole in this the diameter wanted for the hole, and in this hole pour molten lead, and the part touched by the lead will fall out.
To Frost Glass. Cover it with a mixture of 6 ounces of magnesium sulphate, 2 ounces of dextrine, and 20 ounces of water. This produces a fine effect.
To imitate ground glass, use a composition of sandarac, 2 1/2 ounces; mastic, 1/2 ounce; ether, 24 ounces; and benzine, 16 ounces.
Iron and Steel.—How to distinguish them. Wash the metal and put it into a solution of bichromate of potash to which has been added a small amount of sulphuric acid. In a minute or so take out the metal, wash and wipe it. Soft steel and cast iron will have the appearance of an ash-gray tint; tempered steels will be black; and pud[p. 170]dled or refined irons will be nearly white and have a metallic reflection.
To Harden Iron or Steel. If wrought iron, put in the charge 20 parts, by weight, of common salt, 2 parts of potassium cyanide, .3 part of potassium bichromate, .15 part of broken glass.
To harden cast iron, there should be added to the charge the following: To 60 parts of water, add 2 1/2 parts of vinegar, 3 parts of common salt, and .25 part of hydrochloric acid.
To soften castings: Heat them to a high temperature and cover them with fine coal dust and allow to cool gradually.
Lacquers.—For Aluminum. Dissolve 100 parts of gum lac in 300 parts of ammonia and heat for an hour moderately in a water bath. The aluminum must be well cleaned before applying. Heat the aluminum plate afterwards.