B. Dissolve sulphur in bisulphide of carbon.
The cementing is effected by applying solution A to the fractured surfaces and pressing them together. When dry brush solution B over the cemented place.
Elastic gutta-percha cement. Dissolve 10 parts of gutta-percha in 100 of benzine, then pour the clear solution into a bottle containing 100 parts of linseed-oil varnish and unite both by shaking. This cement excels in elasticity, and is especially suitable for attaching the soles of shoes, as it is so elastic that it will not break, no matter how much it is bent. To make it adhere tightly roughen the leather on the side to be cemented.
Cement for horses’ hoofs. For filling cracks and fissures in horses’ hoofs a cement is required which possesses great resistance to the action of water combined with elasticity and solidity. A mass answering all demands consists of 10 parts by weight of gum ammoniac and 20 to 25 of purified gutta-percha. Heat the gutta-percha to between 194° and 212° F., and then work it with the finely powdered gum ammoniac to a homogeneous mass. In using it, soften the cement by heating, and after carefully cleansing the crack in the hoof, apply it with a heated knife. The cement solidifies immediately after cooling to the ordinary temperature, and becomes soon so hard as to allow of nails being driven into it.
Cement for crockery. Gutta-percha 1 part, shellac 1.
Place the two ingredients in an earthenware jar, and melt the two together by standing this jar on a vessel of boiling water, or else one filled with hot sand, the vessel holding the water or sand being heated over a fire or gas furnace. Stir the melted ingredients well together. The resulting cement is one possessing great hardness and toughness, which suits it admirably for mending crockery. Warm the edges to be joined together, smear the cement on, join together, and hold the article thus joined until cool.
Cement for leather. Mix 10 parts of carbon disulphide with 1 part of turpentine, and then add sufficient gutta percha to make a tough, thickly-fluid mass. Before using this cement, free the surface to be joined from grease. To effect this, sprinkle a little bicarbonate of soda, carbonate of ammonia or borax on the surfaces to be joined, lay a cloth over them, and then place a hot iron on top, and keep it there a short time so as to cause the alkali to cut the grease, then put the cement on both surfaces to be joined, put them together and subject to pressure until they are cemented.
Gutta percha dissolved in carbon disulphide to the consistency of syrup is also a good cement for joining leather. The parts to be joined should be well covered with cement so as to fill the pores of the leather, then the cement is heated and the parts hammered until the cement is cold.
CASEINE CEMENTS.
Preparation of pure caseine. Although the caseine contained in old cheese can be used, the other constituents, such as fat, salt, and free acid, exert an injurious influence upon the solidity of the cement prepared with it. It is, therefore, best to prepare pure caseine, which is easily accomplished in the following manner: