44 
a fire escape) it would be preferable to begin with the lower story and 
work upward. 
This insecticide may also be used in other stored products, as peas, 
beans, etc., and very satisfactorily where the infested material can be 
inclosed in a tight can, chest, or closet for treatment. It may also be 
employed to renovate and protect wool or similar material stored in 
bulk. 
The bisulphid costs, in 50-pound cans, 10 cents per pound, and in 
small quantities, of druggists, 25 to 35 cents per pound. 
Caution.—The bisulphid may be more freely employed with milling 
grain than with that intended for seeding, since, when used excess- 
ively, it may injure the germ. It must always be remembered that 
the vapor is highly inflammable and explosive, and that no fire or 
lighted cigars, etc., should be in the building during its use. If ob- 
tained in large quantities it should be kept in tightly closed vessels 
and away from fire, preferably in a small outbuilding. 
While this gas is not especially dangerous to human beings, care 
should be taken to avoid unnecessary inhalation. It has a slight 
suffocating effect, and if inhaled for some time produces dizziness, 
which should be a warning to the operator that it is time to seek fresh, 
pure air. 
SULPHUR DIOXID. 
The fumes of burning sulphur, namely, sulphur dioxid, with some 
sulphur trioxid, have long been one of the standard insecticide gases 
for the destruction of insect pests in rooms or dwellings, and notably 
for the bedbug (Cimewx lectularius li.). Doctor Stiles, of the Public 
Health and Marine-Hospital Service, reports very successful fumiga- 
tion and disinfection of frame cottages at a seaside resort for bedbug 
infestation by burning sulphur at the rate of 2 pounds of stick sulphur 
for each 1,000 cubic feet of space. Sulphur candles for such fumiga- 
tion are a standard supply material to be purchased anywhere. Sul- 
phur fumes are also employed for disinfection from disease germs, 
and also in the more recent yellow-fever work for the destruction of 
mosquitoes in dwellings. The chief objection to the sulphur fumiga- 
tion arises from the strong bleaching action of the fumes in the pres- 
ence of moisture and their powerful destructive action on vegetation. 
For the disinfection of ships and ships’ cargoes, particularly of 
grain, sulphur dioxid, under the name of “ Clayton gas,” is now being 
extensively employed. To determine its efficiency and its effect on 
the grains treated, a considerable series of experiments was conducted 
by the Bureau. These experiments showed that sulphur dioxid, 
under pressure such as can be maintained in an air-tight compartment 
or in the hold of a ship, has great penetrating power and is very efli- 
cient as a means of destroying all kinds of insects. The germinating 

4Bul. 60, Bur. Ent., U. S. Dept. Agric., pp. 189-153. 1906. 
127 
