Boil to gether 1 part of caustic soda, 3 parts of. rosin, 3 parts of gypsum, and 5 parts of water. The cement made in this way hardens in about half an hour, hence it must be applied quickly. During the preparation it should be stirred constantly. All the ingredients used must be in a finely powdered state.

Uniting Glass with Horn

(1) A solution of 2 parts of gelatin in 20 parts water is evaporated up to one-sixth of its volume and 1/3 mastic dissolved in 1/2 spirit added and some zinc white stirred in. The putty is applied warm; it dries easily and can be kept a long time. (2) Mix gold size with the equal volume of water glass.

To Cement Glass To Iron

I

Rosin.............5 ounces

Yellow wax........ 1 ounce

Venetian red....... 1 ounce

Melt the wax and rosin on a water bath and add, under constant stirring, the Venetian red previously well dried. Stir until nearly cool, so as to prevent the Venetian red from settling to the bottom.

II

Portland cement.... 2 ounces

Prepared chalk..... 1 ounce

Fine sand.......... 1 ounce

Solution of sodium silicate enough to form a semi-liquid paste.

III

Litharge...........2 parts

White lead......... 1 part

Work into a pasty condition by using 3 parts boiled linseed oil, 1 part copal varnish.