UNITED STATES DEPARTMENT OF AGRICULTURE 
iPARTMENT BULLETIN No. 1147 
Washington, D. C. 
June 9, 1923 
Revised May, 1924 
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 of arsenicals 2 
Physical properties of arsenicals 20 
Comparative toxicity of arsenicals 24 
General properties of arsenicals 50 
Summary 53 
Literature cited 55 
PURPOSE OF INVESTIGATION. 
A study of the chemical, physical, and insecticidai 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 insecticidai 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. GersdorfT, R. Jinkins, 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. 
100173°— 24— Bull. 1147 1 
