INSECT POWDER. 75 
then filtered off, and dried at room temperature. The residual 
powder, after treatment with 1 per cent hydrochloric acid (HC1), 
1 per cent acetic acid (CH 3 COOH), 1 per cent ammonium hydroxid 
(NH 4 OH), or distilled water, was apparently as active as ever 
(tested against roaches), but after extraction with 1 per cent potas- 
sium hydroxid (KOH) the powder was entirely inert. These tests 
show that the active principle is soluble in dilute KOH, or else is 
rendered inert by it, but is insoluble in, or unaffected by, water, dilute 
acids, or dilute ammonium hydroxid. 
Heated at 107° C. for 17 days the powder took on a markedly 
reddish color. All characteristic odor disappeared after about 3 
days' heating. At the end of the 17-day period the powder was 
tested upon roaches, and found to be entirely inert. Heated in a 
vacuum oven at the temperature of boiling water for 14 hours, the 
powder completely lost its characteristic odor, but was still active 
against roaches. This again indicates that the essential oil does 
not contain the characteristically acting insecticidal principle. 
Different portions of the powder were dried over sulphuric acid 
and solid sodium hydroxid in desiccators in vacuo for 12 days. At 
the end of this time the powders had lost a great portion of their odor 
but were still active against roaches. 
The following tests were made on 300 grams of powder to see 
what amount of extract^ different solvents would remove when used 
one after the other in a Soxhlet extraction apparatus. The succes- 
sion used was petroleum ether, chloroform, acetone, and 95 per cent 
alcohol : 
Solvent. 
Extract. 
Per cent. 
3.4 
5.0 
6.2 
9.0 
Total 
23.6 
Fifty-gram portions of coarsely-powdered material (made from 
partially open flowers) were then completely extracted in Soxhlet 
extraction apparatus by various organic solvents. The object of 
these extractions was to determine what solvents would remove the 
active principle and at the same time extract as little as possible of 
the other substances. In nearly all cases a quantity of resinous 
material separated from solution after the extraction had been run- 
ning for some ^time. This resinous material, which would not go 
into solution, even when treated with large quantities of the solvent, 
apparently resulted from the polymerization of unstable terpehelike 
substances extracted by the solvent, a polymerization probably 
induced by the heat of the boiling solvent. 
