34 MISC. PUB. 526, U. S. DEPT. OF AGRICULTURE 
Plant tissue of all kinds is very susceptible to the action of this gas, 
and the margin of safety between dosages which will kill the insect 
and the plant is very narrow. The materials are generally combined 
in the proportion of 1 ounce of sodium cyanide, 11% fluid ounces of 
sulfuric acid, and 3 fluid ounces of water. 
Plant materials are fumigated in darkness and afterward protected 
for a short period from light to avoid plant injury. 
In certain instances growing plants may be fumigated under canvas 
tents placed over them. For example, the boxwood leaf miner may 
be controlled by this method, sodium cyanide being used at the rate of 
2 ounces per 100 cubic feet of space, with 3 fluid ounces of sulfuric acid 
and 6 ounces of water, for a period of 1 hour. The plants must be 
dormant and dry, and the temperature must not be too high—usually 
402560750 ch. 
Caution.—In carrying out a fumigation a definite procedure and 
certain precautions must be followed. Sodium cyanide should, 
therefore, be used only by experienced fumigators thoroughly fa- 
miliar with the methods of handling it and the hazards involved. 
Hydrocyanic acid gas is colorless and is one of the most deadly 
poisonous gases known. In case of accidental inhalation of the 
gas, the person affected should be kept in the open air and not 
allowed to exert himself. Inhalation of ammonia vapor may be 
of some help. 
All forms of cyanide are extremely poisonous and should be 
plainly labeled and kept in a safe place. To avoid deterioration, 
store the material in tight containers. 
SODIUM FLUORIDE 
Sodium fluoride (NaF) is a white, very poisonous powder, soluble 
in water. The commercial product and commonly employed grade of 
powder is 94 to 97 percent pure. 
Sodium fluoride, undiluted, when dusted in the areas frequented by 
ants and roaches, except the Surinam roach, will gradually eliminate 
them. Sodium fluoride should not be used on plants. 
Caution.—Since sodium fiuoride is poisonous if taken inter- 
nally, it should be kept in tight containers plainly marked 
“Poison” and stored in a dry, safe place away from foods. If the 
dust is inhaled, it is somewhat irritating to the respiratory 
passages. 
In New York City all sodium fluoride must be colored blue, and the 
National Association of Insecticide and Disinfectant Manufacturers, 
Inc., has gone on record favoring this practice throughout the United 
States. This coloring is done to denote its poisonous nature. 
SODIUM FLUOSILICATE 
Sodium fluosilicate (Na,SiF,), or sodium silicofluoride, resembles 
sodium fluoride and is sometimes used undiluted as a substitute for it 
against roaches. Sodium fluosilicate will injure plants unless used in 
