44 
BULLETIN 824, U. S. DEPARTMENT OF AGRICULTURE. 
Table 21. — Chemical analysis of pure insect powder and stem powder (Siedler). 
Determination. 
Product. 
Moisture 
at 110°. 
Ash on air- 
dried material. 
Ether 
extract. 
Pure insect powder 
Per cent. 
10.77 
Per cent. 
6. 81 to 7. 29 
Per cent. 
Powder from best flowers 
6 14 
Stem powder 
8.69 
6.39 
6.36 
1 48 
Unpowdered, but finely-cut flowers 
Siedler used ether with a specific gravity of 0.720, and, after com- 
pletely extracting the sample in the cold, allowed the ether to evap- 
orate spontaneously, and dried the residue for one hour upon the water 
bath. The color of the extract of the powdered flowers was dirty 
yellow, that of the stem powder green. With concentrated sul- 
phuric acid there was no characteristic color reaction with either 
resinous residue. Siedler found the petroleum-ether extract of 
pure powdered flowers to be 4.01 per cent, and that of stem powder, 
1.01 per cent. The flower extract was a pure yellow, that of the 
stems a pure green. With concentrated sulphuric acid the petro- 
leum-ether extract from the flowers gave a deep green color, the stem 
powder a brown. He attempted to obtain a basis for analysis by 
means of the optical behavior of an alcoholic extract from flower 
and stem powders, but this extract proved to be optically inactive. 
In 1913 Siedler (257) commented as follows on the chemical exami- 
nation of insect powder: 
As the best criterion for the value of the insect powder is the determination of 
the ether extract, which was first made by Thorns. Later this method was modified 
in this way, that the powder was shaken with ether and an aliquot part of the decanted 
ether solution allowed to evaporate. This procedure has certain drawbacks. It is 
not possible to decant a definite quantity of ether solution without causing a difference 
in weight by evaporation of ether. Further, the ether solution can not be obtained 
clear except after long standing and it is very difficult to filter clearly. It always 
deposits fine dust after filtration. Finally, there is generally the feeling that the 
powder is not completely extracted through simple shaking, that a part of the ether- 
extractable material escapes determination. 
In the same article Siedler gives results for the determination of 
ash in insect powders (Table 22). All these samples were ground 
from the best flowers free from stems, and had an average moisture 
content of 4 per cent. The total ash and the ash insoluble in dilute 
hydrochloric acid were determined on 2.5 grams of substance. 
Table 22. — Determination of ash in insect powder (Siedler). 
Sample No. 
Total. 
Insolu- 
ble in 
HCL 
Sample No. 
Total. 
Insolu- 
ble in 
HCl. 
1 
Per cent. 
&6 
1.0 
7.0 
7.9 
Per cent. 
0.1 
.1 
.2 
.2 
.1 
6. 
Per cent. 
8,0 
7.9 
7.7 
7.8 
Per cent. 
0.1 
2 
3 
7 
8 
.1 
.1 
4 
9 
.1 
5 
lu... 
6.8 
.1 
