150 FUMIGATION METHODS 
acid was then dropped in and the door quickly closed. 
The vials were dropped in with the mouths down, and 
the contents drained out gradually, avoiding a puff of 
the gas by too rapid generation. The box was kept 
closed for ten minutes, or as long as desired. Both 
doors were then thrown open and the trays lifted out, 
so that the plants were thoroughly aired. 
‘The cyanide solution should be secured from a 
druggist, put up in homeopathic vials, one dose in each 
vial. The solution consists of too grammes 98 per cent. 
potassium cyanide dissolved in water to make 200 
cubic centimeters solution. The amount necessary for 
each dose is easily computed: multiplying the cubic 
contents of the box by o.4 will give the number of 
cubic centimeters of the solution to be used, this giving 
a strength of o.2 gramme potassium cyanide per cubic 
foot. Use an equal amount of sulphuric acid, which 
cain be readily measured into empty vials. Thus fora 
box 2x 2x 2% feet, or 10 cubic feet, 4 cubic centi- 
meters of the solution, or a two-drachm vial half full, 
and an equal amount of sulphuric acid (best grade 
commercial, 1.85 specific gravity) would be used for 
a strength of 0.2 gramme potassium cyanide per cubic 
foot, or the same vial three-quarters full for a strength 
of 0.3 gramme potassium cyanide per cubic foot. 
Small plants in the field.—For individual plants, 
such as melon, cucumber, cabbage, etc., a small cover 
is needed. In many cases where only a few plants are 
to be treated, a two-gallon wooden pail or other simi- 
lar vessel will do. Paper or canvas covered boxes, one 
or two feet square at the base, and fifteen to twenty 
inches high, can be made cheaply and used to good 
