INSECT POWDER. 21 
Miscellaneous adulterants — Continued . 
Pepper. 
Quassia (wood of Picrasma excelsa (Swartz) Planchon; and of Quassia amara L.). 
Quillaja, soap-bark (dried bark of Quillaja saponaria Molina, deprived of its 
periderm). 
Sawdust. 
Senna leaves (dried leaves of Cassia acutifolia Delile; or of Cassia angustifolia 
Vahl.). 
Starch, potato. 
Starch, wheat. 
Starch, variety not specified. 
Stems and leaves of insect powder plant. 
Sumach (dried fruit of Rhus glabra L.). 
HOW TO DETECT ADULTERATION. 
The methods which have been used in determining the genuineness 
of insect powders may be classified in 3 groups: 
1. Physiological. — The powder to be tested is tried out directly on 
one or more species of insects, and the time necessary to produce 
death compared with the time in which the same quantity of a known 
genuine insect powder will kill the insect. 
2. Microscopical. — Adulterants are detected by observation 
through the microscope, either with or without staining or other 
preliminary chemical treatment. 
3. Chemical. — The ash, ether extract, and other chemical deter- 
minations are made and the results compared with the average values 
for genuine powders. 
PHYSIOLOGICAL METHODS. 
Kalbruner (151), in 1874, was the first to record the physiolog- 
cal testing of insect powder. He states that 4 grains of a good 
insect powder sprinkled on a fly in a vial should produce stupor in 
1 minute and death in 2 or 3 minutes. Testing a number of commer- 
cial powders in this manner, he found that from 15 to 30 minutes 
were required to kill flies. Flowers representing a number of 
species of plants, as well as the powdered stems and leaves of Pyre- 
thrum roseum and cinerarisefolium, were tested in this way, and 
found to be quite worthless, as compared with genuine insect powder. 
In 1876, De Bellesme (63), in his research on the active principle 
of Pyrethrum, in order to show that its action was not the mechanical 
one of closing the pores of an insect, sprinkled flies with insect powder 
and also with powdered leaves, wood, and various other inert sub- 
stances. Those sprinkled with the Pyrethrum powder were almost 
dead after 1 hour, while those left for 10 hours in the inert powders 
were uninjured. 
