Inse:cts and Inse:cticide:s 
51 
The following formula has been adopted in most states as the 
standard for fumigating nursery stock: 
Potassium cyanide (of 98 percent purity) . 1 ounce 
Commercial Sulfuric acid . 2 ounces 
Water . 4 ounces 
The above quantities are sufficient for loo cubic feet of space. 
Submit the nursery stock to the fumigation for from 40 to 60 min¬ 
utes. For fumigating dwellings, mills, clothing, and the like, it may 
be used even stronger, and should run several hours. 
This gas is sometimes used in fumigating green houses, but as 
there is great danger of it injuring the tender plants, it should be 
used only by those of experience. For this purpose, the quantities 
given in the above formula are used to each 1000 cubic feet, of space. 
Fumigate only at night, and while plants are dry, as sunlight and 
moisture make the gas more injurious to vegetation. Leave the 
house closed for 5 or 6 hours before airing, and air well before en¬ 
tering. 
In mdxing the materials, use only an earthern or wooden vessel, 
and add the materials in the following order: 
First, put in the water, then add the acid slowly. Put the re¬ 
quired amount of cyanide in a thin paper bag, and when all is ready, 
drop it into the liquid and leave the room as quickly as possible. 
The gas is very poisonous and almost odorless. One breath of it 
when strong may mean death. Never enter the fumigation room 
until it has been aired 30 minutes. 
All buildings should be made as tight as possible before fumiga¬ 
tion starts. Nursery stock may be fumigated in a tight box or a 
house prepared especially for this work. Such a house should be 
built with two thicknesses of matched boards, with building paper 
between. Ventilators should be provided and doors made tight- 
fitting. 
Handle the potassium cyanide with great care remembering it is 
a deadly poison. 
REPELLANTS 
24. Napthale:ne: Flakes, Gum-camphor, and Moth Balls 
These are used as repellants against fleas, clothes moths, museum 
pests, chiggers, etc. Scatter the repellants about the infested ma¬ 
terials. They are often used in insect boxes and packed in with furs, 
feathers, and woolen goods to keep out insects that feed upon these 
animal products. They are not used to kill insects. 
25. Commercial Repellants 
There are several commercial repellants upon the market that are 
of some value in protecting stock from flies. These can be secured 
at most any drug store. 
