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The quantity required to kill insect pests varies with the temperature 
of the room or fumigator in which it is used. For ordinary conditions, 
5 quarts (14 pounds) per 1,000 cubic feet of space is recommended, if the 
temperature is 65 degrees F. or higher. The specimens should be exposed 
to the gas for at least 24 hours. Two or three weeks later the fumigation 
should be repeated, so that any eggs that may have escaped the first 
treatment may be given an opportunity to hatch out in time for the second. 
Advantages. Highly toxic to insects, non -explosive, non-inflammable, 
non-toxic to man unless highly concentrated and breathed for protracted 
periods of time, non-in jurious to specimens, inexpensive, easily applied. 
Disadvantages. Apparently none. 
Carbon Disulphide 
This gas has long been used in museum work and has given excellent 
results. It is highly toxic to insects and when used in concentrations of 
about 8 pounds to each 1,000 cubic feet of space at a temperature of 65 
degrees F. for 24 hours or more is 100 per cent lethal. The gas given off is 
heavier than air and the pans containing the liquid should, therefore, be 
placed near the top of the case, room, or fumigator. Its great disadvantage 
is its dangerously explosive and inflammable nature, and it is probable 
that the new mixture of ethylene dichloride and carbon tetrachloride will 
displace it entirely. 
Advantages. Highly toxic to insects, non-injurious to specimens, in- 
expensive, easily applied. 
Disadvantages. Poisonous, highly inflammable, explosive. 
Carbon Tetrachloride 
This material can be used alone as a fumigant and will give satisfactory 
results if used in concentrations of about 20 pounds to each 1,000 cubic 
feet of space. In this case, too, the gas is heavier than air and the recept- 
acles should be placed above the specimens. 
Advantages. Toxic to insects, non-injurious to specimens, non- 
explosive, non-inflammable, non-poisonous, inexpensive, easily applied. 
Disadvatages. Less toxic than the mixture of ethylene dichloride and 
carbon tetrachloride, requiring about four times as much liquid to produce 
satisfactory results. 
Hydrocyanic Acid Gas 
This material has the great advantage that it is very highly toxic and 
will certainly exterminate any insects that are exposed to it. It may be 
applied in any one of three ways: the pot method in which the gas is 
generated on the spot by the action of sulphuric acid and water on sodium 
cyanide; the calcium cyanide method, in which the chemical is sprinkled 
on sheets of paper laid on the floor and allowed to evaporate; and the 
liquified hydrocyanic acid method in which the poison is shipped in high 
pressure tanks and liberated in the fumigator in pre-determined quantities. 
