12 
formol was used. This is a mixture of formalin with 20 per cent of 
calcium chlorid and 10 per cent of glycerin. About 4 ounces of the 
solution remained in the retort after the operation. The time of exposure 
was twelve hours, making the conditions correspond about to the require- 
ments as laid down in the United States Quarantine Eegulations. The 
temperature of the room during this experiment was 72° to 87° F. 
The mosquitoes and the cultures were exposed in the pill boxes, placed 
side by side, so that the conditions were as nearly alike as possible. 
Mosquitoes. 
Bacteria. 
Dead. 
Alive. 
Subtilis 
spores. 
Pyocya- 
neus. 
In pill boxes — 
Under 1 layer damp towel 
2 
2 
+ 
Under 2 layers damp towel 
3 
1 
+ 
— 
Under 4 layers damp towel 
0 
2 
-f 
— 
Under 4 layers dry towel 
2 
5 
-F 
— 
Wrapped in 4 layers dry towel 
0 
1 
-f 
— 
Wrapped in 4 layers damp towel 
0 
3 
-f 
— 
In damp pocket of overalls, hung up 
0 
4 
-f 
— 
In dry pocket of overalls, hung up 
10 
5 
+ 
— 
In mail bag, mouth tied 
0 
8 
+ 
— a 
Under pile of towels, loosely heaped 
1 
4 
+ 
— 
On wall behind a duck coat 
3 
3 
Lost. 
— 
Control, in air-tight jar, with moisture 
2 
2 
+ 
-f 
a Contaminated. 
From this test it is plain that the requirements of the United States 
Quarantine Eegulations, which are sufficient to destroy non-spore- 
bearing bacteria in the pockets of clothing or under 4 layers of towels, 
are impotent to destroy mosquitoes similarly protected. Some of the 
insects survived in each one of the boxes. Even in the control box 
2 of them were dead. It is, therefore, plain that the occasional deaths 
in all the other cases can not be attributed to the effects of the gas. 
The analogy between the resistance of the spores and the resistance 
of the mosquitoes is strikingly shown in this test. 
No. 9. 
The second experiment with the autoclave was done in the same room 
as the above, but under different conditions. The exposure was short 
and the percentage of formaldehyd very high. Two thousand cubic centi- 
meters, or about 65 ounces, of the glyco-chloro-formol solution was used. 
This is 3 times the amount required for ordinary disinfection. After a 
pressure of 60 pounds to the square inch was obtained, the gas was 
allowed to enter the room. The operation was continued at this pressure 
for fifteen minutes. One-half of the liquid remained in the autoclave 
at the close of the operation. 
The total time of exposure was two hours and fifteen minutes, counted 
from the time the gas was first allowed to enter the room. The tem- 
perature of the room during 4he test was 81° to 89° F. 
