42 



BULLETIN 824, V. S. DEPARTMElvrT OF AGRICULTURE. 



powders guaranteed by first-class houses to be ground from selected 

 closed flowers have yielded from 7.13 to 10.25 per cent ether extract. 

 Evans Sons, Lescher and Webb (76) give the results shown in Table 

 19 on the ether extract determination of insect powders. 



Table 19. — Ether extract determination on insect powders. 



Year. 



Labeled as- 



Ether 

 extract. 



1906 



Closed flowers 



Per cent. 

 8 to 9 



1906 



Open flowers 



5 to 6 



1906 



Stalks 



Up to 5 

 8. 5 to 8. 8 



1907 



Closed flowers 



1907 



Open flowers 



6. 8 to 6. 2 



1909 



Powder from closed flowers 



6.9 



1909 



do : 



6.6 



1909 



Powder from half-open flowers 



5.9 



1909 



Powder from open flowers 



6.2 









' One sample examined in 1909 gave only 4.3 per cent of an extract 

 heavily, contaminated with chlorophyll. Microscopical examination 

 of the powder showed the presence of tissue derived from the stalk 

 of the plant. Eight American commercial insect powders examined 

 in 1910 contained from 3 to 4.8 per cent ether-soluble matter,. 

 the green color of the extracts indicating admixture of open flowers 

 and stem tissues, A few foreign-ground powders examined in 1906 

 yielded from 2 to 3 per cent ether extract. The powders reported 

 in Table 19, examined in 1906 and 1907, were of their own grinding. 



Southall Brothers and Barclay in 1910 (268) reported finding from 

 7.57 to 8.28 per cent ether extract in authentic samples of insect 

 powder when determined according to Durrant's method. Japanese 

 flowers, mostly open, gave 13.98 per cent ''resin" of an orange- 

 brown color. In 1912 (269) they found 3.81 per cent of a deep- 

 green extract in a specimen of insect powder said to be ground from 

 stalks. Leubner (172), in 1910, found 5.59 per cent of a dirty-green 

 extract in a sample of insect powder. He macerated the sample 

 with an excess of ether for 3 hours, and dried the extract at 100°. 



Caesar and Loretz (43), in 1911, gave their method for the determi- 

 nation of ether extract of insect powder as follows : Seven grams of 

 the air-dried powder are treated in a 1 50 cc. flask with 70 grams ether, 

 macerated 2 hours, the mixture being frequently shaken up by hand, 

 then filtered through a 9 cm. filter; 50.5 grams (=5 grams powder 

 air-dried) of the filtrate are then evaporated in a 9 to 1 cc. porcelain 

 dish over hot water, being careful not to set the dish on the ring of 

 a steam bath, as the solution in that case will creep over the edge. 

 The evaporation is carried to drjmess, and the residue brought to con- 

 stant weight in a desiccator. The extract should have a golden- 

 yellow color and a characteristic, powerful odor, which should not 



