The following is a new process for preparing artificial meerschaum. Precipitates are prepared by means of a solution of soluble glass: (a) of silicate of magnesia, by precipitating it through a solution of sulphate of magnesia; (6) of silicate of alumina, byprecipitating through a solutionof alum; (c) of silicate of lime, by precipitating through a solution of chloride of calcium. All these solutions are diluted, 1 part salt being used for 10 parts water. In order to precipitate the solutions, the operation is performed at 20° C, except in the case of the silicate of alumina, for which the solutions have a temperature of about 50° C. (d) A solution of fused chloride of calcium (1 part to 15 of water) is precipitated at 15°-20° C. by a solution of sulphate of soda (1 to 15). The precipitate of sulphate of lime is first dried, and then freed of the larger part of the water that it may contain, by compressing it, and exposing it upon hurdles in a stove. Finally, it is totally dehydrated by heating it in a very clean iron kettle. The sulphate of lime thus prepared is in the form of a very fine and very white powder.
It is carefully preserved in boxes that are kept in a perfectly dry place.
Into 33 lb. of water at 40° C. are put 19 lb. of precipitate d in 20 successive and nearly equal portions. The mixing should be done with much care and with rapid stirring. There are afterwards added to the mixture the following substances, weighed in advance: 73/4- lb. of precipitate a; 3 3/10 lb. of precipitate &; 5 1/2 lb. of precipitate c. All these precipitates should be mixed with water, and then the mass, which is in the form of a thin bouiiii, is immediately introduced into a vessel through a No. 20 brass sieve, and thence into wooden boxes that rest upon large slabs of plaster covered with canvas, and about 4 in. thick. In about 15-25 minutes the mass may be detached from the sides of the frame by means of a blunt blade of brass, and the frame may be removed. The mass is left upon the slabs of plaster until it is sufficiently dry to be sawed into small blocks of various dimensions, according to requirements. These blocks are more thoroughly dried upon hurdles in a stove. Then they are worked with a knife or in a lathe, and are waxed and polished as in the case of objects made of genuine meerschaum. It should be remarked that, on introducing the hot mixture into the frame, care should be taken not to introduce air bubbles at the same time.
Varying proportions of precipitates a, 6, c, may be used. The larger the proportion, the harder and heavier will be the final mass.