INSECT POWDER 37 
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 
examination 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 Thoms. Later this method was modi- 
fied 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 deter- 
mination. 
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) 
Tnsolu- Insolu- 
Sample No. Total ble in Sample No. Total ble in 
HCl HCl 
Per cent | Per cent 
9 0.1 
{Leaner ernie ie een = wee BR AT OSI eG st) TES eT Sate 
Deets aot Se 3 Pe Pe TEU py | lind ee eae ee BO 7.9 1 
Gis Se Sh ee tet tee 7.06 Se ee eee © Ue ie a ee Uo 1 
ue ee ote Bae Pee ee 7.0 Srl BS sabe seeps was SN Se Rae ae eS 7.8 1 
jee ern pee at 8. Le tao SIE E1OS! 2 Soe Sel eee ke wee 6.8 1 
Fromme (86) reports that the ash content of insect powder is 
between 6.5 and 9.5 per cent. Later (87) he criticizes the method of 
Trottner, whereby the value of the powder is determined by the num- 
ber of pollen grains present. Fromme found that some of the most 
active powders contain fewer pollen grains than other powders pre- 
pared largely from stems. The analytical results on seven samples 
tested are given in Table 23. 
TaBLEe 23.—Hzamination of active insect powder (Fromme) 
Pollen 
Ash Eile Color of ether extract grains in 
mg. 
Percent | Per cent : 
8. 21 Ga GOlG EHV EL O Wee ee 2 re See Oe a Sa a Sees eee es 308 
vent’ GaGOn ne reenishoyellow.. oe ee ee gos Eras sin  AS  h a ceel do O 2, 415 
7.25 §, 1.5 l= CCinieinee ey aes Ge, Set) es oe tee eS eee BE ee eee 2, 900 
8. 00 Pe EPO IST Oll yea me he oy a ae een ete AE ee 230 
8. 84 Herel GinGeneyOlow re aoeee ts 2 SESS ee) ee a Te a a 3, 000 
8. 00 STEEP UD a Ba fag ears ee PE gs aaa a Se eee SA Aes ee 710 
7.10 Ea EEE CT IEG Reenter eee Meee ees ee SR ee ee A ed Re? 294 
