INSECT POWDER. 
73 
himself and Schlagdenhauffen. According to Reeb, the toxic prin- 
ciple of insect powder is an acid called pyrethrotoxic acid, which pre- 
exists in the free state in the flowers of Pyrethrum. 
In 1912 Yoshimura and Trier (295) published the results of their 
work upon the closed flowers of C. cinerarixfolium in search of 
betains. From 1 kilogram of air-dried powder they obtained 0.2 
gram cholin and 0.8 gram stachydrin, both calculated as hydro- 
chlorids. They made no tests as to the insecticidal action of these 
substances, but they are probably inert. 
Siedler (258), 1915, distilled 30 kilograms of half-closed flowers 
with dry steam, extracted the distillate with ether, and thus obtained 
a salve like mass of strong characteristic odor. The yield was 20.212 
grams, or 0.067 per cent of the original material. Spread on un- 
glazed porcelain, all was absorbed but 0.789 gram. By fractional 
recrystallization from aqueous alcohol 2 bodies were obtained from 
this unabsorbed portion: (1) Fine needles, melting point, 54-56°; 
and (2) fine plates, melting point, 58-60°. Recrystallized from 
absolute alcohol this substance had a melting point of 62°. Ele- 
mentary analysis of (1) showed it to correspond closely to the 
formula C 14 H 30 . Analysis of (2) showed a formula approximating 
palmitic acid. The material absorbed by the porous plate was 
extracted with ether, and this concentrated solution mixed with 2 
parts ether and 1 part alcohol. By extraction with sodium bisul- 
phite solution, 0.049 gram of material was obtained of an aromatic 
odor, but without effect upon insects. By extraction with 2 per 
cent potassium hydroxid solution, 3.156 grams of material were 
isolated. No test for phenol could be obtained. An acid of butyric 
odor was obtained, but it was inert toward insects. Other tests, 
such as distillation of the material under reduced pressure, are 
recorded by Siedler, but nothing possessing insecticidal action could 
be isolated. 
Evidently, then, a number of investigations on the nature of the 
active insecticidal principle of Pyrethrum have been carried out, 
but the results are at great variance. Table 45 gives a brief sum- 
mary of these investigations. 
Table 45. — Summary of investigations on active insecticidal principle of Pyrethrum. 
Year 
1854 
1863 
1863 
1876 
1876 
1877 
1878 
Investigator. 
Ragazzini (de Visiani) . . . 
Heller & Kletzinsky 
(Hanamann.) 
Hanamann 
Rother 
De Bellesme 
Semenoff 
Bibliog- 
raphy 
reference, 
67 
114 
114 
234,235 
63 
253 
111 
Species of Pyrethrum 
used. 
Cinerarizefolium 
Roseum (?) 
.do. 
Active principle considered 
to be— 
A mixture of substances, nature 
not determined. 
An essential oil and santonin. 
An essential oil, "persicin." 
(?) 
(?) j A "crystallized principle. 
Roseum (?) An essential oil. 
Roseum and Carneum I A resin and an amin. 
