﻿UNITED STATES DEPARTMENT OF AGRICULTURE 



DEPARTMENT BULLETIN No. 1147 



Washington, D. C. ▼ June 9, 1923 



CHEMICAL, PHYSICAL, AND INSECTICIDAL PROPERTIES OF ARSENICALS. 



By F. C. Cook, Physiological Chemist, Insecticide and Fungicide Laboratory, Miscel- 

 laneous Division, Bureau of Chemistry, and N. E. McIndoo, Insect 

 Physiologist, Fruit Insect Investigations, Bureau 

 of Entomology. 1 



CONTENTS. 



Page. 



Purpose of investigation 1 



Arsenicals studied 1 



Chemical properties ot arsenicals 2 



Physical properties of arsenicals 20 



Comparative toxicity of arsenicals 24 



G eneral properties of arsenicals 50 



Summary 53 



Literature cited 55 



PURPOSE OF INVESTIGATION. 



A study of the chemical, physical, and. insecticidal properties of 

 arsenicals on the market was undertaken in order to gain a better 

 understanding of them, to be able, if possible, to improve them, and 

 to produce new arsenicals for insecticidal purposes. The results of 

 this investigation, which was conducted by the Bureau of Chemistry 

 and the Bureau of Entomology of the United States Department of 

 Agriculture, are here reported. 



ARSENICALS STUDIED. 



Paris green and lead arsenate, which have been standardized and 

 found reliable for many years, have constituted the principal in- 

 secticides used against external chewing insects. However, during 

 the past few years, the use of calcium arsenate has steadily in- 

 creased, owing in part to the discovery that it is effective in combating 

 the boll weevil. The manufacture of calcium arsenate, although well 

 beyond the experimental stage in most factories, probably will not 

 be completely standardized for several years. Because of the im- 

 portance and recent large-scale production of calcium arsenate, many 

 of the results in this bulletin deal with comparisons of calcium 

 arsenate and acid lead arsenate. 



1 The following assisted in this work: R. Elmer, W. A. Gersdorff, R. JinMns, B. Neuhausen, and A. 

 Schultz, Junior Chemists, Insecticide and Fungicide Laboratory, Bureau of Chemistry, and W. A. Hoff- 

 man. Scientific Assistant, and W. B. Wood, Entomological Assistant, Bureau of Entomology. 



27476°— 23— Bull. 1147 1 



