198 



LovETT (A. L.). The Calcium Arsenates.— J/. Econ Entom Concord 



N.H., xi, no. 1, February 1918, pp. 57-62. ' 



Owing to War conditions having seriously affected the supply of 

 lead arsenate, it has become necessary to find an efficient and practical 

 substitute as a stomach poison for insects. Calcium arsenate has 

 long been recognised as a cheaper material than lead arsenate, but 

 has been considered unsatisfactory as it causes scorching of the foliage. 

 It could be obtained at one-half the cost of lead arsenate, even before 

 the War. As the cause of scorching is generally the arsenic contained 

 in the spray, and as considerable difficulty was encountered in the 

 same way with lead arsenate when it was first used, it was assumed 

 that a more complete knowledge of the properties of calcium arsenate, 

 its composition and preparation, might lead to some practical method 

 for its substitution for the more expensive lead arsenates. 



With the object of studying the properties of the calcium arsenates, 

 two pure calcium salts, acid calcium arsenate, CaHAsO^ and the 

 neutral or basic calcium arsenate, Ca (ASO4)", were prepared and 

 tested. The former was found to be more soluble and less stable when 

 subjected to unfavourable conditions than was the latter. Either of 

 the pure salts or the commercial salts when in solution with an excess 

 of ordinary quicklime (CaO) or with lime-sulphur gave no unfavourable 

 reaction and judging from a chemical laboratory test should prove 

 safe spray materials. Care should be taken that the lime used is 

 fairly pure CaO and not CaCOg. 



In preliminary field spraying experiments, the commercial materials 

 showed decidedly better adhesive properties than the pure materials. 

 Control trees that were sprayed without the addition of either lime or 

 lime-sulphur exhibited decided scorching, but the addition of an excess 

 of CaO in the lime-sulphur and calcium arsenate spray was apparently 

 a sufficient protection. In preparing the solution for field spraymg, 

 the lime should be slaked and added to the water in proper proportions 

 in the spray tank and the solution agitated for some 15 minutes before 

 the calcium arsenate is added. 



Hartzell (F. Z.). The Influence of Molasses on the Adhesiveness of 

 Arsenate of Lead. — Jl. Econ. Entom., Concord, N.H., xi, no. 1, 

 February 1918, pp. 62-66. 



During 1910-1916 the author used molasses to render lead arsenate 

 more attractive to Macrodactyliis subspinosus (rose chafer) and to 

 Fidia viticida (grape root-worm) -with much success, largely, it is 

 believed, owing to the lack of rain in the period immediately following 

 the application. Certain attempts indicated that the shorter the time 

 between the spraying and the first rain, the less perfect was the control 

 of the insect. Tests of adhesiveness were then made in the laboratory, 

 photographic plates being used as a substitute for the leaf surface. 

 These results are shown in a table. The percentage of material remain- 

 ing on the plates after sprinkling was found to differ considerably 

 with the different brands of lead. No dry arsenate of lead proved as • 

 adhesive as the better adhering paste lead arsenates, though several 

 of the brands of paste lead arsenate had poorer adhesive qualities than 

 the dry lead arsenates tested. The addition of molasses to lead arsenate 



