2249. Caoutchoucine

2249. Caoutchoucine. Pure India rubber, cut into small lumps, is thrown into a cast-iron still, connected with a well-cooled worm tub, and heat is applied until the thermometer ranges about 600° Fahr., when nothing is left in the still but dirt and charcoal. The dark colored fetid oil which has distilled over is next rectified with one third its weight of water, once or oftener, until it is colorless; it is then highly volatile and of .680 specific gravity. The product is then shaken up with nitro-muriatic acid, or chlorine, in the proportion of 1/4 pint of acid to each gallon of the liquid. This is the lightest fluid known, and yet its vapor is the heaviest of gases. Mixed with alcohol, it dissolves all the resins, especially copal and India rubber, at the common temperature of the air; and it speedily evaporates, leaving them in a solid state. It mixes with the oils in all proportions; and has been used for making varnishes, and for liquefying oil paints, instead of turpentine. It is very volatile, and must be kept in close vessels.

2250. Cement for Uniting Sheet Guttapercha to Silk, etc.

2250. Cement for Uniting Sheet Guttapercha to Silk, etc.. Gutta-percha, 40 pounds; caoutchouc, 3 pounds; shellac, 3 pounds; Canada balsam, or Venice turpentine, 14 pounds; liquid storax, 35 pounds; gum mastic, 4 pounds; oxide of lead, 1 pound. Mix as directed in the next receipt.

2251. Cement for Uniting Sheet Gutta-Percha to Leather

2251. Cement for Uniting Sheet Gutta-Percha to Leather. For uniting sheet gutta-percha to leather, as soles of shoes, etc. Gutta-percha, 50 pounds; Venice turpentine, 40 pounds; shellac, 4 pounds; caoutchouc, 1 pound; liquid storax, 5 pounds. In making the cement, the Venice turpentine should be first heated ; then the gutta-percha and the shellac should be added; the order in which the other materials are added is not important. Care should be taken to incorporate them thoroughly, and the heat should be regulated, so as not to burn the mixture.

2252. Transparent Cement

2252. Transparent Cement. Dissolve 75 parts India rubber in 60 parts of chloroLUTE.

form, and add to the solution 15 parts of gum mastich.

2253. How to Fasten Rubber to Wood and Metal

2253.      How to Fasten Rubber to Wood and Metal. As rubber plates and rings are now a-days almost exclusively used for making connections between steam and other pipes and apparatus, much annoyance is often experienced by the impossibility or imperfectness of an air-tight connection. This is obviated entirely by employing a cement which fastens equally well to the rubber and to the metal or wood. Such cement is prepared by a solution of shellac in ammonia. This is best made by soaking pulverized gum-shellac in ten times its weight of strong ammonia, when a slimy mass is obtained, which, in three to four weeks, will become liquid without the use of hot water. This softens the rubber, and becomes, after volatilization of the ammonia, hard and impermeable to gases and fluids.