QUASSIIN AS A CONTACT INSECTICIDE. 5 



It being observed that tannin is not extracted from an aqueous 

 solution by chloroform, an attempt was made to collect the chloroform- 

 soluble material which was not precipitated by the tannin. The 

 solution was accordingly shaken with chloroform, and the chloroform 

 separated in a separating funnel. When replaced in aqueous solu- 





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H -It 



Fig. 1. — Compressed-air spray machine used in applying 

 quassiin solution. (Original.) 



tion ; the extracted material was found to be intensely bitter and gave 

 all the appearance of being quassiin. It is evident that all of the 

 quassiin is not precipitated by tannin. 



Because the material used proved effective as an insecticide at 

 dilutions of 0.4 grams to 1,500, 1,800, and 2,000 cubic centimeters, 

 the writer believes that it was comparatively pure quassiin. 



INSECTICIDAL VALUE OF QUASSIIN. 



The determination of the insecticidal value of quassiin is the main 

 object of this investigation. In accomplishing this object an attempt 

 is made to compare the action of quassiin to the action of a standard 

 contact insecticide. Nicotine sulphate is taken as the standard, 



