Ether for this purpose should be agitated with water, and decanted. Benzol will dissolve caoutchouc with warmth and long digestion. Rectified coal naphtha forms an imperfect solution employed in Macintosh's waterproof fabrics. Oil of turpentine, rendered pyrogenous by absorbing it with bricks of porous ware, and distilling it without water, and treating the product in the same way, is also used for this purpose. It is stated that the solution on evaporation does not leave the caoutchouc in a sticky state. Another method is to agitate oil of turpentine repeatedly with a mixture of equal weights of sulphuric acid and water; and afterwards to expose it to the sun for some time. Bisulphide of carbon is a good solvent, dissolving the gum without heat. This constitutes Parkes' Patent Solvent. Chloroform is an excellent but rather expensive solvent.* Caoutchoucin has also been employed as a solvent. It is prepared by distilling India rubber without addition, increasing the heat to 600° Fahr. The product is rectified by distilling it with one third of water. It is then a colourless fluid of 0'6S0 specific gravity. Its smell is improved by agitating it with 5 oz. of nitro-hydrochloric acid to each gallon. India rubber is rendered more readily soluble by first digesting it with a solution of carbonate of soda, or water of ammonia.

*Methylated chloroform is much cheaper than that made from rectified spirit.