The recent discovery of a lead substitute for the making of insecticides, as disclosed at the convention of the American Chemical Society in Louis, is anticipated as being responsible for the saving of millions of dollars of farm products. Credit' for devising a method of preparing a commercial grade of calcium arsenate belongs to the scientists of the Insecticide and Fungicide Board, U. S. Department of Agriculture, The use of calcium arsenate as a substitute for lead arsenate is a notable contribution to the industry of manufacturing insecticides because of the cheapness of lime as compared with lead oxide. Of course, calcium arsenate cannot be sprayed alone on tender foliage but when combined with sul fides its application in fighting crop pests is effective.
The method of making calcium arsenate from lime and arsenic acid is prescribed as follows by the Insecticide and Fungicide Board; Obtain a good quality of lime, slake the product to as smooth a paste as feasible, for such a procedure not only determines the smoothness of the finished product. but the willingness with which the lime and acid rea Apply from 3 to times as much water, by weight, as lime," and have the water warm, After standing for a while mix thoroughly, then adding twice as much hot water as used for slaking, mixing the products again,
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