12,312. Carolan, E. A., [General Electric Co.]. May 29. Washers for electric insulating purposes. An intimate mixture is formed of equal quantities of calcium hydrate, or other comparatively-soluble compound of an alkaline earth, and a refractory fibrous binding material, such as asbestos fibre or mineral wool, to which mixture about 10 per cent. of its weight of borax glass may be added. Enough water is added to make the mass plastic. The mixture is then compressed to form the washer, which, after partial drying, is soaked in a solution of a soluble carbonate, such as that of sodium or ammonium, a current of carbonic-acid gas being continuously passed through the solution. When the whole of the calcium hydrate has been converted into insoluble carbonate, the material is thoroughly washed with running water to remove all the soluble bodies, after which it is heated to a temperature of between 200‹ and 300‹ C. until it is thoroughly dried.