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- 
Fic. 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 quasstin. It is evident that all of the 
quassun 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, 
