34 BULLETIN 824, U. S. DEPARTMENT OF AGRICULTURE 
source gave ether-soluble matter from 7.3 to 12.4 per cent, while 5 
samples from another source gave 7 to 12 per cent. Grieb makes 
a paca y test with 1 gram of powder, shaking it with 10 cc. of 
ether in a test tube, and if, after settling, the ether is of a marked 
green color (“indicating the presence of ground stalks”’), the assay 
is not proceeded with and the sample is rejected. 
Jean (1/47), in his analysis of a number of samples of Pyrethrum 
powder, determined moisture, ash, “acidity,” alcohol-ether extract, 
resinous substances, substances soluble in water, and the iodin 
absorbed by the water solution after rendering it alkeline by bicar- 
bonate of soda (Table 18). In order to compare these results, Jean 
eve a powder from genuine Pyrethrum flowers, called the “type” 
sample. 
TABLE 18.—Chemical analysis of Pyrethrum powder (Jean) ! 
Determination on dry basis 
| 
Gamaple Acidity | Alcohol- | Resinous| Soluble | y gin ab- 
Ash as ether sub- in Speed Moisture 
H2SOz | extract | stances | water e 
| 
Per cent | Per cent | Per cent | Per cent | Per cent | Per cent | Per cent 
Dypettt futir piste: ag 8, 90 1. 00 24. 03 9.30 14.73 | S Sa! ietiee 
FANE Oe Mectads high RL Sak ES eT 7.47 . 99 24. 94 8. 01 16. 93 7. 65 11.5 
USE ee Fee ee aes Ss 10. 04 1.09 30. 47 13. 76 16. 70 5. 22 9.9 
OSA se WADA Be hee Ee | 8. 70 . 64 21. 91 9. 41 12. 50 3.15 8.0 
SS) eae ay rag ro gh etn ae) 9. 02 1. 03 24, 40 11.14 5.8 12.5 
1 Jean does not give his methods of analysis. 
2? Contained potassium chromate and sawdust. 
Sato (236) states that mature flowers of the Chrysanthemum 
cinerarrefolium should be used in preparing insect powder. The 
most desirable moisture content is 7 to 8 per cent; the ash is 6 to 7 
per cent, and always shows the reaction for manganese. The greater ~ 
the content of ether-soluble matter the greater the value of the 
powder. If the ether extract is green, leaves and stalks have been 
mixed with the flowers. The amount of ether extract should not be 
less than 6 per cent, and the ratio of ether extract to ash should be 
oreater than 1. H. W. and S. C. Gadd (90) give methods for de-- 
tecting turmeric and chrome alum in insect powder. For the deter- 
mination of ether-soluble material they use Durrant’s method. 
According to them the ash of a genuine powder should be of a light 
gray color and should not amount to over one-sixteenth of the 
original. 
Vogt (286) in 1906 wrote that he invariably found a rich yellow 
percolate to be characteristic of the finest insect powders. He ob- 
tained 7.72 per cent of ether extract in a sample of insect powder 
ground by himself from closed flowers, and stated that samples of 
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 & Webb (76) give the results shown in Table 
19 on the ether extract determination on insect powders. 
