42 
BULLETIN 824, TJ. S. DEPARTMENT OE AGEICULTURE. 
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 powderrs. 
Year. 
Labeled as- 
Ether 
extract. 
1906. 
1906. 
1906. 
1907. 
1907. 
1909. 
1909. 
1909. 
1909. 
Closed flowers 
Open flowers 
Stalks 
Closed flowers 
Open flowers 
Powder from closed flowers 
do 
Powder from half-open flowers. 
Powder from open flowers 
Per cent. 
8 to 9 
5 to 6 
Up to 5 
8. 5 to 8. 8 
5. 8 to 6. 2 
5.9 
5.2 
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 150 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 10 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 dryness, 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 
