26 BULLETIN 824, U. S. DEPARTMENT OF AGRICULTURE 
CHEMICAL METHODS 
In all of the published work relating to the chemical analysis of 
insect powder the determinations have been practically confined to 
those of ash and of ether-soluble material, together with specific tests 
for turmeric, lead chromate, and other adulterants, the presence of 
which might be suspected. As long as the active principles of the 
powder were unknown, a comparison of the ash content, color, and 
quantity of ether extract of the sample undergoing examination with 
those of powders of known purity afforded the only method of judg- 
ing the génuineness of a commercial powder by chemical means. 
The first published analyses of insect powders are those reported 
in 1879 by Hilgard (131), who determined the ether extract of four 
samples with the results shown in Table 4. 
TaBLe 4.—Kther-extract content of insect powder (Hilgard) 
Ether 
Eroduct extract 
Per cent 
{SPersianvlnsect (Pow d Or see reget oe eres ee a ce cena Sea pe Re oes oe 9.5 
‘’Buhach?’«(sample ‘grown 1878) sees ae a Ee Ea ee See ee ee ee eee ; 6.1 
S“Bihach?s (Sample: crown sit 1879) ae eee Ne ee a at re ee ee ee ee 5.8 
poliyou's Magnetic: POWGEr ace 2 Tee Sie pe Se ie ee toe ee ee 4.9 
His tests of these extracts on insects showed that the quantity of 
the extract present was not necessarily a measure of the efficiency 
of the powder. 
Grote (108), in 1880, found lead chromate in a sample of insect 
powder. He believes that the odor of an insect powder furnishes 
more evidence of its genuineness than the color. Kral (164), in 
1880, found curcuma in a series of insect powders, but no lead chro- 
mate. Howie (139), in 1883, reported the results of the chemical 
examination of 12 insect powders. He considered the chemical 
method for the detection of added coloring matter as more accurate 
than the microscopical method. ‘The results obtained on these 12 
samples are shown in Table 5. 
TaBLe 5.—Chemical examination of insect powder (Howite) 
Sample Vendor’s definition Color Adulterant Ash 
Per cent 
dsm Sect apowid Chess ae eee Drape fe. eee Genuine 4 oe See eee 6. 2 
Del sane (6 a pera teh OM Foal cher cota aealivs Faces al ea dos an |e eee O22 SS SSS See RR Bie] eae Td 
By Ppebede meebo 2 fu oP Seaside vote Dees Oliverdrabases see ole ae et oe eee a Sapp aa ote 6.0 
4 | From closed flowers_.---_..------- “Yellowish sees see (6 C0 Pes SRE aT eatin Des RE Ker 6.8 
jn) PAL-closed flowers a= oo eee Oe eee AE | Re Keep eee tert g | aay Sees 6.2 
6) Open flowersss: 2 ee oe eee (0 Yo UR aes See P| GOs FS eR 2 Rec ene 6.2 
fl Ee ACKEG DO WiC Cleese ne = eee eee SY all OWE 1: Seen Chrome. 222-4 ese0 Stee 10. 5. 
tte eee Gos {pita o Pee re ees eS ee (oe ee gees la ae Ost Foe ere ERT eee 9.6 
ONO pte. Pe eer SOE Fe See ees | ele GOszee hha | See QOf aa ae 9. 2 
10} | PAlieclosed* flowers ease eee eee (a Koyercse Ree Turmeric and chrome_-_-_-__---- 8.0 
ME Moneion’: te . ea a eee | gee do.oe eee Chrome 4 ee ee 9.4 
JTPeal Fal D el nay i a ini, gees te al SY Very yellow__-_- Turmeric. #432 = ees 6.0 
