76 



BULLETIN 824, IT. S. DEPARTMENT OF AGRICULTURE. 



After extraction the material was tested on roaches, ants, and other 

 insects by the entomologists of the Bureau of Entomology, of this de- 

 partment, at the Vienna testing laboratory, Vienna, Va. In all 

 cases the extracted material was entirely inert when tested against 

 these insects, showing that all the solvents used completely remove 

 the insecticidal principle. 



Table 46 shows the solvents used, the total amount of extracted 

 material removed by each solvent, and the amount of insoluble resin 

 separating out m each case. 



Table 46. — Amount of material extracted hy various solvents from the flowers of C. cinera- 

 riasfolium {Sample No. 26962). 



Solvent. 



Chjoroform 



Carbon tetrachlorid 



U.S. P. ether. 



Petroleum ether 



Carbon disulphid 



Methyl alcohol 



Ethyl alcohol (absolute)... 

 Ethyl alcohol (95 per cent) 



Acetone - 



Benzol 



Ethyl acetate 



Total 

 extract. 



Per cent. 

 8.93 

 6.51 

 7.85 

 3.77 

 4.57 

 28.78 

 19.18 

 30.91 

 16.66 

 5.74 

 15.48 



Insoluble 

 resin. 



Per cent. 



0.04 



.80 



.77 



.37 



.62 



11.38 



1.12 



4,18 



2.20 



.00 



1.30 



No insoluble resin is formed in extracting with benzol, and only 

 a trace with chloroform. The large amount of insoluble extract in 

 the case of methyl alcohol is explained by the fact that the solution 

 went nearly to dryness through loss of the solvent by evaporation. 



In view of the fact that all the solvents completely removed the 

 insecticidal principle, as shown by practical tests, and petroleum 

 ether extracted the smallest amount of material, it was decided to 

 use petroleum ether as the solvent in further work and to use a perco- 

 lator in making the extractions, to avoid heating the material in 

 solution. 



For the percolation a quantity of the highest grade closed Japanese 

 insect flowers procurable were coarsely powdered, packed in a glass 

 percolator, macerated with the solvent for 48 hours, and the percola- 

 tion then allowed to proceed slowly, the solution being drawn off at 

 the rate of about 1 drop a second. In this way a beautiful, sUghtly 

 greenish-yellow solution was obtained. This was placed in large 

 glass crystallizing dishes, and the solvent allowed to evaporate at 

 room temperature in a current of air. The residue remaining was 

 partly solid and partly an oily liquid, at ordinary temperature, of a 

 reddish-yellow color, and had a strong characteristic odor. Nothing 

 crystalline was observed in this residue. Careful tests showed that 

 it did not contain any nitrogen. 



