INSECT POWDER. 75 



thon filtered off, and dried at room temperature. The residual 

 powder, after treatment with 1 per cent hydrochloric acid (HCl), 

 1 per cent acetic acid (CH3COOPI), 1 per cent ammonium hydroxid 

 (NH,,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. 



Petroleum ether . 



Chloroform 



Acetone 



Alcohol 



Total 



Per cent. 

 3.4 

 5.0 

 6.2 

 9.0 



23.6 



Fifty-gram portions of coarsely-powdered material (made from 

 partially open flowers) were then completely extracted in Soxlilet 

 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 frpm 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 terpenelike 

 substances extracted by the solvent, a pol^nnerization probably 

 induced by the heat of the boiling solvent. 



