32 
Bulletin 71. 
For the destruction of the woolly-louse of the apple, thrust a 
crow-bar or other sharp instrument into the ground to the depth of 
one foot and at a distance of twx> feet from the crown of the tree and 
upon three sides of the tree. In each of these holes pour one ounce 
of the carbon bisulfide and close the holes quickly with damp earth. 
This is a cheap and effectual remedy and, if care is taken to have 
the holes made two feet from the tree and to have only about an 
ounce of the liquid put in a hole, there will be no danger of killing 
the trees. 
This substance is expensive when purchased in small quantities 
at a drug store. It may be obtained quite cheaply if purchased in 
50-pound lots, from Mr. Edward R. Taylor, Cleveland, Ohio. Write 
for prices. 
29. HYDROCYANIC ACID GAS. 
This gas has come into very general use, particularly in the 
orange growing sections of the country, for the destruction of scale 
insects. It may also be used for the destruction of insects in mills 
and in dwellings and in closed receptacles generally. Some of the best 
nursery men have adopted the plan of fumigating all their nursery 
stock with hydrocyanic acid gas before shipping to their customers. 
The chemicals of which this gas is made are cheap and are 
used in the following proportions: 
Potassium cyanide (of 98 per cent, purity).1 ounce 
Commercial sulfuric acid.1 ounce 
Water.3 ounces 
The above quantities are sufficient for a space of 100 cubic feet 
for the fumigation of dormant trees and plants (nursery stock). It 
may be used in the same strength, or even stronger, for the fumi¬ 
gation of mills, houses, clothing and the like. 
The tent, building or receptacle in which the fumigation is to 
take place, should be as tight as possible. The less wind there is 
the better, if the fumigating room is not very tight. 
The gas should be generated in an earthen jar, or wooden 
bucket or tub. The chemicals must be added in the following order: 
First put in the water; then add the acid; and, after the water and 
acid have mixed, add the potassium cyanide. A good way to add 
the poison is to have it tied in a paper sack and placed upon a piece 
of board over the dish containing the acid and water, with a string 
attached to the sack and passing to the outside. Then, when every¬ 
thing has been made tight, a pull on the string will precipitate the 
sack of cyanide in the acid and a rapid escape of the poisonous 
fumes (HCN) will immediately take place, causing violent bubbling 
of the liquid. Filling ones lungs with these fumes would cause 
almost instant death, so that great care must be taken not to breath 
them. Fumigating rooms must be arranged so that doors or win¬ 
dows of some sort can be raised from the outside quickly. Then a 
thorough airing must take place before anyone enters. 
