Cement, Elas′tic. Prep. 1. Caoutchouc (in small pieces), 1 part; chloroform, 3 parts; dissolve.
2. (Lenher.) Caoutchouc, 5 parts; chloroform, 3 parts; dissolve, and add gum mastic (powdered), 1 part. Elastic and transparent.
3. Gutta percha, 3 parts; caoutchouc, 1 part (both cut small); bisulphide of carbon, 8 parts; mix in a close vessel and dissolve by the heat of a water bath. This is to be gently warmed before it is applied.
4. Gutta percha, 1 lb.; caoutchouc, 4 oz.; pitch, 2 oz.; shell-lac, 1 oz.; linseed oil, 2 oz.; melted together. This must be melted before being applied.
Obs. The cements 1 and 2 are elastic and transparent, and are applicable to many uses. The others, 3 and 4, are used for uniting leather, cloth, &c.
Cement, Elec′trical. Syn. Chemical cement. From black resin, 7 lbs.; red ochre, 1 lb.; plaster of Paris, 1⁄2 lb. (both well dried and still warm); melted together, and the heat and agitation continued until all frothing ceases, and the liquid runs smooth; the vessel is then withdrawn from the fire, and the mixture stirred until cooled sufficiently. Used to cement the plates in galvanic troughs, join chemical vessels, &c. See Cement, Cap, Cement, Singer’s, &c.
Cement, Engineers′′. Prep. 1. Ground white lead, mixed with as much red lead as will make it of the consistence of putty.
2. Equal weights of red lead and white lead, mixed with boiled linseed oil, to a proper consistence. Used by engineers and others to make metallic joints. A washer of hemp, yarn, or canvas, smeared with the cement, is placed in the joint, which is then “brought home,” or screwed up tight. It dries as hard as stone. It also answers well for joining broken stones, however large. Cisterns built of squares stones, put together, while dry, with this cement, will never leak or come to repair.
Cement, Extempora′′neous. 1. Shell-lac, melted, and run into small sticks the size of a quill. Used to join glass, earthenware, &c. The edges are heated sufficiently hot to melt the cement, which is then thinly smeared over them, and the joint made while they are still hot. This is the cement so commonly vended in the streets of London, and which used to surprise us in our boyhood days.
2. Tears of gum mastic, used in the same way. Commonly employed by jewellers and others.