Circular 21 - Insecticides and Subsidiary Materials 39 
Caution ; Because of their extremely 
poisonous nature, all forms of cyanide should 
be handled with the greatest of care and only 
by competent persons thoroughly familiar with 
the hazards involved. It is always necessary 
to wear a gas mask provided with the proper 
canister for absorbing hydrocyanic acid gas 
when working with the fumigant. The materials 
should be kept in tight containers, labeled 
plainly, and kept in a safe place. While the 
gas burns freely in air, it is not considered 
dangerously inflammable or explosive at the 
concentration normally employed in fumigation. 
For complete safety, however, all fires should 
be extinguished when fumigating. Also the 
draft or currents of air caused by a fire will 
exhaust the gas from a building and thereby 
reduce its effectiveness. The liquid hydro- 
cyanic acid deteriorates slowly and under no 
conditions should cylinders of liquid be 
stored for more than five months. 
In the fumigation of food products, the 
liquid hydrocyanic acid should not be used in 
such a v;ay that the liquid will come into con- 
tact with the product; otherwise undue absorp- 
tion may occur and render the food dangerous 
for consumption. 
Liquid hydrocyanic acid is sold for 31 
per pound. Discoids sell for $1.20 per pound 
in 1-pound cans. Sodiuia cyanide can be pur- 
chased in 100 pound lots for about 16 cents 
per pound. Calcium cyanide dust containing 
50 percent available hydrocyanic acid ranges 
in price from SI. 60 per pound in 1-pound cans, 
to £^1.20 per pound in 25-pound cans. 
Sodium cyanide is available on contract: 
see Class 51, General Schedule of Supplies, 
Procurement Division, Treasury Department. 
