162 JOURNAL OF ECONOMIC ENTOMOLOGY [Vol. 7 



Mr. George A. Dean: I wish to express my appreciation of the 

 President's address and as one of the younger entomologists, it is 

 certainly an inspiration to me to have reviewed the progress which has 

 been made in entomology during the past fifty years and, particularly, 

 the outline of progress made within the last few years. The work has 

 now progressed to a point where we are reaching the farmer and he is 

 securing direct benefit from it. 



Mr. a. F. Conradi: I was interested in that part of the address 

 where the speaker referred to the increased possibilities for research 

 work since the passage of the Adams Act. In South Carolina this has 

 resulted in preventing duplication of work and in increasing the force 

 of men employed. The work has been centrahzed under one head so 

 that it has become more efficient. 



Chairman W. E. Hinds: If there are no other remarks I will 

 retire and the regular program will be continued. Before doing so, 

 however, I wish to congratulate our President on the address which he 

 presented. 



President P. J. Parrott: The first paper on the program will be 

 presented by Mr. J. A. Dew, entitled, Some Properties of Various 

 forms of Arsenate of Lead. 



SOME PROPERTIES OF VARIOUS FORMS OF ARSENATE 



OF LEAD 



J. A. Dew 



Up to the present time little detailed investigation of insecticides 

 has been conducted in the Southern States. Owing to the fact that 

 there are large numbers of leaf-eating insects present the greater part 

 of the year, arsenate of lead is by far the most widely used insecticide. 

 Arsenate of lead was first used for poisoning leaf-eating insects in 1892, 

 and during the past twenty years great manufacturing interests have 

 developed to supply the present day demand. Naturally, with a 

 large number of manufacturers in the field, there are several different 

 forms of arsenate of lead on the market, most of which can be placed 

 in two classes, viz: first, acid, meta, or bi-plumbic (PbHAsd4) and 

 second, neutral, ortho, or tri-plumbic (Pb3(As04)2); but recently 

 there has appeared what is known as basic arsenate of lead. This 

 last-mentioned form contains an excess of the base and was put on 

 the market for special use in humid areas where the other forms caused 

 injury. 



The present paper is a preliminary report of the work done by the 

 writer during the past year to determine just what forms of arsenate 

 of lead are the most effective and what characteristics give the insec- 



