Adhesives for Various Uses.—Waterproof glue. Use a good quality of glue, and dissolve it in warm water, then add one pound of linseed oil to eight pounds of the glue. Add three ounces of nitric acid.

Leather or Card-board Glue. After dissolving good glue in water, to which a little turpentine has been added, mix it with a thick paste of starch, the proportion of starch to glue being about two to every part of glue used. The mixture is used cold.

A fine Belt Glue. Dissolve 50 ounces of gelatine in water, and heat after pouring off the excess water. Then stir in five ounces of glycerine, ten ounces of turpentine, and five ounces of linseed oil varnish. If too thick add water to suit.

For cementing Iron to Marble. Use 30 parts of Plaster of Paris, 10 parts of iron filings, and one[p. 163] half part of sal ammoniac. These are mixed up with vinegar to make a fluid paste.

To cement Glass to Iron. Use 3 ounces of boiled linseed oil and 1 part of copal varnish, and into this put 2 ounces of litharge and 1 ounce of white lead and thoroughly mingle so as to make a smooth paste.

Water-proof Cement. Boiled linseed oil, 6 ounces; copal, 6 ounces; litharge, 2 ounces; and white lead, 16 ounces. To be thoroughly incorporated.

To unite rubber or leather to hard substances. One ounce of pulverized gum shellac dissolved in 9 1/2 ounces of strong ammonia, will make an elastic cement. Must be kept tightly corked.

For uniting iron to iron. Use equal parts of boiled oil, white lead, pipe clay and black oxide of manganese, and form it into a paste.

Transparent Cement. Unite 1 ounce of india rubber, 67 ounces of chloroform, and 40 ounces of mastic. This is to be kept together for a week, and stirred at times, when it will be ready for use.

To Attach Cloth to Metal. Water 100 parts, sugar 10 parts, starch 20 parts, and zinc chloride 1 part. This must be first stirred and made free of lumps, and then heated until it thickens.