INSECT POWDER 31 
extract of insect powders made in this way varied from 5.16 to 5.38 
per cent. 
Durrant (73) is the author of the ether extraction method that 
has been most generally applied in the valuation of insect powder. 
He proceeds as follows: 
Place 100 grains of the powder in the cylinder of a glass syringe (1 ounce). 
The powder should be pressed down compactly on to a piece of absorbent cotton 
to act as a filter. Moisten with ether (0.735 sp. gr.); close the top of the syringe 
and macerate for 30 minutes; percolation may then proceed, the powder being 
repercolated with the same fluid four times, and finally washed through with 
sufficient ether to make up 1 fluid ounce. The resulting percolate should be of 
a rich yellow color; if a pronounced green color be the result the sample may 
be disearded at once. 
This percolate should be evaporated at 200° F., and should weigh not less than 
3.75 grains (=3.75 per cent), and should have the characteristic odor of the 
flowers * * *, Insect powder ground from selected closed flowers is sensibly 
free from chlorophyll, whereas traces of it (less than 0.5 per cent) will be found 
in powders prepared from mixed and half-open flowers, and in the foreign ground 
insect powders it often amounts to from 50 to 80 per cent of the total ether extract. 
Durrant suggests the determination of the amount of chlorophyll 
when it is present in large quantities, by converting it to glucose and 
determining that in the regular way. He concludes: “The value of 
insect powder is in direct proportion to the combined amount of 
essential oil and soft acid resin and in inverse proportion to the 
amount of chlorophyll—both statements to be read together.” 
Francis (84) determined the ether extract of a powder made from 
a P ”? a B) 
eround flowers only,” one from ‘‘ground stems only,” and of a 
“mixture of these two in equal proportion,” to be as follows: Ether 
extract of flowers, 6.07 per cent; ether extract of mixture, 3.82 per 
cent; ether extract of stems, 2.25 per cent. He states, ‘‘ The ether 
extracts in each instance had a decided green color, indicating the 
presence of chlorophyll.” 
Dowzard (71) estimates ether-soluble matter as follows: ‘‘ Two 
grams of the sample are mixed with 50 cc. of ether in a stoppered 
cylinder, the mixture being shaken at intervals during 2 hours; 25 
ec. (=1 gram powder) of the clear ethereal solution is evaporated 
in a tared beaker and the residue weighed.”’ He also makes use of 
physiological tests: ‘Two grams of the sample is transferred to a 
beaker, a cockroach is then introduced and the number of minutes 
which elapse before the insect becomes stupefied are noted.” He 
gives the results of the examination of 12 samples shown in Table 14. 
TABLE 14.—Ezamination of insect powder (Dowzard) 
seuiod of a . Period of - Eerod of ae 
. physio- er physio- Ether NT physio- ther 
Sample No.| ‘ogical | extract || Sample No. logical | extract || S8™Ple No. | ‘logical | extract 
test test test 
Minutes | Per cent Minutes | Per cent Minutes | Per cent 
ee 4 Sai Seba sz 5 CHa Gee A 7 5.0 
tae ee Se 5 eG Ges ek el 5 SiO lO Sai ae 8 | 3.2 
a 5 FAAP Yee 5 Sede — eee | 12 4.2 
(ae oe ee ae 5 6.6 Sas he ee 5 | oH DSc eta ea | 12 | 3.0 
Dowzard adds: “TI think the figures prove that the value of insect 
powder as an insecticide is in proportion to the amount of ether- 
soluble matter present. Of course, it is impossible to obtain exact 
