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The following" precautions and miscellaneous directions should 
be observed: 
As cyanide of potassium is a powerful poison it should be 
handled as little as possible, and if touched with the bare hands 
they should be thoroly washed at once. It should be stored in 
tightly closed cans or jars, plainly labeled, and kept where it will 
be inaccessible to persons not acquainted with its poisonous prop¬ 
erties. Only a grade which is 98 to 99 percent pure should be 
used. 
Sulphuric acid should not come in contact either with hands 
or clothes, as it will severely burn the flesh and ruin the clothes. 
It must not be placed in metal receptacles, as it will soon eat 
thru them. 
Always put the water into the jars first, adding the acid later. 
Never pour water into the undiluted acid. After placing it in the 
jars the bags of cyanide should be added as soon as possible, for 
any delay will interfere with the proper reaction of the chemi¬ 
cals, owing to the fact that the acid acts most powerfully when 
it first unites with the water. The manner of putting the cyanide 
into the acid is also important. The bags should not be held a 
foot or more above the jars and dropped in, as the concussion 
might cause them to be thrown out by the reaction. Each bag 
must be carefully laid in the jar, but the fumigator must not lean 
over the jar as he does it, nor remain near it to watch the re¬ 
action. 
The best-shaped jar, when using 2 ounces of cyanide to a jar, 
is one 4 or 5 inches in diameter and about 9 inches high. If 
more cyanide is to be used in each receptacle a larger jar must 
be used. 
The foliage of plants to be fumigated should be perfectly dry, 
otherwise the gas will be absorbed and the foliage injured. 
Fumigate in the cooler parts of the day, and avoid, if possi¬ 
ble, a temperature above 6o° to 65° F., since at a higher one 
plants are more liable to be injured. 
After a few fumigations the operator often becomes less at¬ 
tentive to the prescribed directions and precautions. This tend¬ 
ency should be promptly checked, the utmost care and caution 
being uniformly exercised. 
Fumigation with tobacco stems or with any of the commercial 
tobacco extracts is partially effective, and where the use of hy¬ 
drocyanic acid gas is impracticable this treatment is recommended. 
More fumigations will be required, but if persistently followed 
up, the white fly can be kept in check by this means. 
In houses which are not sufficiently tight for successful fumi¬ 
gation, the plants should be sprayed with a solution of whale-oil, 
