INSECT POWDER. 



73 



himself and SchlagdenhaufTen. Accordiiio; 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. cinerarisefoliwm 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 salvelike 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 C14H30. 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. — Sumviary of investigations on active insecticidal principle of Pyrethrum. 



Year. 



Investigator. 



Bibliog- 

 raphy 

 reference. 



Species of Pyrethrum 

 used. 



Active principle considered 

 to be— 



1854 



Ragazzini (de Visiani) 



Heller & Kletzinsky 

 (Hanamann.) 



Hanamaim 



Rother 



De BeUesme. . 



67 



114 



114 



234,235 



63 



253 



111 



Cinerarisefolium 



A mixture of substances, nature 



1863 



Roseum (?).. 



not determined. 

 An essential oil and santonin. 



1863 



..do.... 



An essential oil, "persicin." 



1876 



(?) 



1876 



(?) 



A "crystallized principle." 

 An essential oil. 



1877 



SemenofE 



Hager 



Roseum (?) 



1878 



Roseum and Carneum 

 (7). 



A resin and an amin. 



