76 
BULLETIN" 824, U. 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 in each case. 
Table 46. — Amount of material extracted by various solvents from the flowers of C. cinera- 
risefolium (Sample A T o. 26962). 
Solvent. 
Total 
extract. 
Insoluble 
resin. 
Chloroform 
Carbon tetrachlorid ... 
U.S. P. ether. 
Petroleum ether 
Carbon disulphid 
Methyl alcohol. 
Ethyl alcohol (absolute)... 
Ethyl alcohol (95 per cent) 
Acetone 
Benzol 
Ethyl acetate... 
Per cent. 
8.93 
6.51 
7.85 
3.77 
4.57 
28.78 
19.18 
30.91 
16.66 
5.74 
15.48 
Per cent. 
0.04 
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, slightly 
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 ordinaiy 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. 
