Circular 21 - Insecticides anjl Subsidiary Materials 62 
32 to 4-3/A cents per pound for the yellow, 
and 5 to 8 cents per pound for the white form, 
Available on contract: For Yellow see 
Class 29, for Liquid see Class 51, General 
Schedule of Supplies, Procurement Division, 
Treasury Department. 
PETROLEUM (CRUDE OIL) 
Petroleum or crude oil is sometimes 
used to kill fly larvae which develop in 
manure piles, garbage, feces, or other refuse. 
For this purpose, application is made by 
sprinkling the surfaces of such breeding 
places so as to form a protective oil covering. 
Crude petroleum is obtained from the 
ground as an oily, inflammable liquid ranging 
from almost colorless to nearly black, but 
usually of a dark greenish or brownish hue. 
The specific gravity varies considerably, 
depending on the source, but crude oil is 
usually lighter than water. It is a complex 
mixture of hydrocarbons in which small quan- 
tities of other materials such as sulfur, 
nitrogen compounds, water, and silica are 
also present. Crude oil is refined by a 
process of distillation which yields gasoline, 
kerosene, fuel oil, lubricating oil, and other 
petroleum products. The chief oil-producing 
regions of the United States at present are 
California, Oklahoma, and Texas. 
Caution ; Crude oil is inflammable. 
Oily rags in poorly ventilated places often 
cause fire by spontaneous combustion. 
