APPENDIX 
HYDROCYANIC ACID GAS AGAINST HOUSEHOLD INSECTS 
The following directions for fumigating with hydrocyanic acid 
gas are taken from Professor Herrick’s circular published by the 
Cornell Reading Course: 
Hydrocyanic acid gas has been used successfully against house¬ 
hold insects and will probably be used more and more in the future. 
It is particularly effective against bed-bugs, and cockroaches, but 
because it is such a deadly poison it must he used very carefully. 
The gas is generated from the salt potassium cyanid, by treating 
it with sulfuric acid diluted with water. Potassium cyanid is a 
most poisonous substance and the gas emanating from it is also 
deadly to most, if not all, forms of animal life. The greatest care 
must always be exercised in fumigating houses or rooms in buildings 
that are occupied. Before fumigation a house should be vacated. 
It is not necessary to move furniture or belongings except brass or 
nickel objects, which may be somewhat tarnished, and butter, milk, 
and other larder supplies that are likely to absorb gas. If the nickel 
and brass fixtures or objects are carefully covered with blankets 
they will usually be sufficiently protected. 
There may be danger in fumigating one house in a solid row of 
houses if there is a crack in the walls through which the gas may find 
its way. It also follows that the fumigation of one room in a house 
may endanger the occupants of an adjoining room if the walls be¬ 
tween the two rooms are not perfectly tight. It is necessary to keep 
all these points in mind and to do the work deliberately and thought¬ 
fully. The writer has fumigated a large college dormitory of 253 
rooms, once a year for several years, without the slightest accident 
of any kind. In order to fumigate this building about 340 pounds 
of cyanid and the same amount of sulfuric acid were used each time. 
In addition to this, the writer has fumigated single rooms and smaller 
houses with the gas. In one instance the generating jars were too 
small; the liquid boiled over and injured the floors and the rugs. 
Such an accident should be avoided by the use of large jars and by 
placing old mgs or a quantity of newspapers beneath the jars. 
