98 
Experiment No. J± — Pyretlirum. —Two pounds per 1,000 cubic feet; 
exposure, two hours; result, all mosquitoes killed. 
Mosquito cages were placed in several parts of the room. At the 
end of the experiment some of the insects showed signs of life, but 
none revived. 
Experiment No. 5—Pyrethrum. —One pound per 1,000 cubic feet; 
exposure, two hours; result, all mosquitoes killed. 
The pyretlirum was burned in an open brazier upon the floor in 
the same room used for the preceding experiments. The mosquitoes 
were freely exposed to the effects of the fumes in appropriate cages, 
which were placed upon the floor, near the ceiling, and one inside a 
box laid upon a table. 
At the end of the experiment the cages were immediately taken to 
the fresh air and many of the Stegomyia showed signs of life, but 
none revived. 
Experiment No. 6 — Sulphur. —Three and one-fourth pounds per 
1,000 cubic feet; exposure, two hours; result, all mosquitoes killed. 
In this experiment four large rooms and the hallway of our lab¬ 
oratory building were fumigated to destroy some mosquitoes that had 
escaped. The rooms communicated with each other and with the 
hallway through large openings. No attempt was made to seal the 
doors and windows or to paste cracks. 
Three pots of sulphur were distributed at points of vantage, each 
pot containing 20 pounds, the total space to be fumigated being 
12,280 cubic feet. 
Two hours after the sulphur was lighted the house was opened and 
it was found that only about two-thirds of the sulphur had burned; 
that is, about 3J pounds per 1,000 cubic feet. In this experiment the 
pots containing the sulphur were not placed in water, the object being 
to obtain a dry gas and thereby minimize the destructive action of the 
fumes upon the fabrics and pigments. 
Four cages containing mosquitoes were placed in different parts 
of these rooms and all were killed. 
As a result of these disinfection experiments we conclude that: 
While we found tobacco smoke efficacious in destroying the insects, 
we also found that the method is exceedingly objectionable on account 
of the persistent and disagreeable odor that it leaves, as well as on 
account of the yellow stains which remain. Tobacco smoke in con¬ 
centrated form stains fabrics, paint work, and other surfaces, but 
the stains may be removed by washing; still, this forbids its use in 
parlors and the rooms of fine houses. 
We found that the burning of 1 pound of tobacco per 1,000 cubic 
feet, with an exposure of one hour, was only sufficient to stupefy the 
insects. All Stegomyia fasciata were killed by an exposure of two 
