58 BULLETIN 137, U. 8. DEPARTMENT OF AGRICULTURE. 
enameled dipper has been found convenient in placing the cyanid 
in the generators. The reaction of the chemicals is extremely rapid, 
and the generation of the deadly gas begins at once. In fumigating 
large buildings, where a considerable number of generators are re- 
quired, the operator should have several assistants. In such cases 
it is best to have the proper amount of cyanid in paper sacks placed 
beside the jars holding the acid and water. Begin dropping the 
eyanid in the jars farthest from the door first, going from one jar 
to the next as rapidly as possible. 
TEMPERATURES FAVORABLE FOR EFFECTIVE FUMIGATION. 
In using fumigants for the control of the tobacco beetle, best re- 
sults have been secured in warm weather and at temperatures above 
70° F. Under 60° or 65° F. the beetles are more or less dormant 
and while in this condition are considerably more resistant to the 
action of the gas. 
DOSAGES TO USE. 
Sodium cyanid (NaCn).—This substance when pure liberates 
nearly one-third more hydrocyanic-acid gas per pound than does 
potassium cyanid and at present it is more generally used for fumi- 
gation. 
Sodium cyanid should be combined with acid and water to gen- 
erate the hydrocyanic-acid gas according to the following formula: 
Sodium cyanid (grade guaranteed to contain not less than 
Hil percent CyanOseM) see sae aes ees avoirdupois ounce__ 1 
SULphHUGTieeacid «( COMMPETCIa)) =e ae eee fluid ounces__ 1% 
VV Cr ee a ee ce a See fluid ounces__ 3 
Use multiples of the formula given above to secure the dosage 
desired. Fumigate for 24 hours. The dosage to use will depend upon 
the penetration required. For general use 4 ounces of the cyanid 
to 100 cubic feet will be found satisfactory. (This dosage requires 
4 ounces of the cyanid, 6 fluid ounces of acid, and 12 fluid ounces of 
water.) For baled or closely packed tobaccos a somewhat heavier 
dosage may be used, or the time of exposure increased. An increase 
of the amount of cyanid above 4 ounces per 100 cubic feet, however, 
has not greatly increased the effectiveness of the treatment in many 
instances. ) 
Potassium cyanid.—Should potassium cyanid be used in place of 
the sodium cyanid, it should be combined with the sulphuric acid 
and water according to the following formula: 
Potassium cyanid (98-99 per cent) ____avoirdupois ounce__ 1 
Swiphurie acid (commercial) ae fluid ounce__ 1 
We Peres ie ee ae lg cee a fluid ounees__ 3 
