. Bulletin of the Department of Agriculture. Agriculture; Agriculture. 12 BULLETIN 731, U. S. DEPARTMENT OF AGRICULTURE. of calcium arsenate was still more effective. This contains a much higher 2)ercentage of arsenic pentoxid than any other arsenical utilized and has the great advantage of being much cheaper than lead arsenate. In addition, a number of tests of various mixtures of these arsenicals and dilutions of them with different carriers were conducted. This work is still in the experimental stage and it is difficult to prophesy just what the results will be. It is obvious, however,
. Bulletin of the Department of Agriculture. Agriculture; Agriculture. 12 BULLETIN 731, U. S. DEPARTMENT OF AGRICULTURE. of calcium arsenate was still more effective. This contains a much higher 2)ercentage of arsenic pentoxid than any other arsenical utilized and has the great advantage of being much cheaper than lead arsenate. In addition, a number of tests of various mixtures of these arsenicals and dilutions of them with different carriers were conducted. This work is still in the experimental stage and it is difficult to prophesy just what the results will be. It is obvious, however, that either a dihydrogen lead arsenate containing not less than 32 per cent of arsenic pentoxid or a calcium arsenate containing at least 42 per cent of arsenic pentoxid will produce an effective control if utilized properly. It also seems probable that it will. Fig. 9.—Hand dust guns in operation, showing method of use; Tallulah, La., July 15, 1916. be possible to dilute these considerably with some cheap carrier such as lime, though this has not been definitely determined as yet. DENSITY OF THE POISON. Fully as important as the actual composition of the chemical is its physical condition. When the experiments were first started, practically all of these chemicals were prepared only in a density of about 40 cubic inches per pound. It was evident, however, that a much finer powder would afford a greater distribution per pound, and also that a finer powder was apparently more readily taken ii]) by the dew and held in suspension for the weevils. Consequently these poisons were prepared in density ranging from 80 to 160 cubic inches per pound and proved much more effective in that Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original United States. Dept. of Agriculture. [Washington, D. C. ?] : The Dept. : S
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