11 
were distilled. The time of exposure was twenty hours. The mosqui- 
toes and the cultures were exposed in pill boxes under similar conditions, 
as follows : 
Mosquitoes. 
1 Bacteria. 
• 
Dead. 
Alive. 
; Subtilis 
1 spores. 
Pyocya- 
neus. 
In pill boxes — 
Controls, exposed to the gas without protection 
5 
0 
I 
Under 2 layers of dry toweling 
4 
0 
— b 
— 
Wrapped tightly in dry towel, 6 layers 
7 
0 
— 
— 
Under 2 layers of a damp towel 
6 
0 
-1- 
— 
In pocket, duck coat, hung up, with pocket toward wall... 
7 
0 
+ 
— 
In pocket of overalls, folded once and laid on floor, 
pocket next to floor 
4 
2 
-h 
— 
In trousers pocket, deep, hung up 
0 
4 
+ 
— 
In corner of a folded newspaper, under 7 layers 
2 
6 
-h 
— 
On floor under towels, heaped in a pile 
2 
4 
+ 
— 
In canvas mail sack, mouth closed 
3 
3 
1 -h 
— 
In bottom of a battery jar, under 2 layers toweling 
6 
0 
1 -h 
1 
— 
a Delayed. b Contaminated. 
The insects survived the twenty hours exposure in the pockets of over- 
alls and trousers, under 7 layers of newspapers, under a heap of towels, 
and in a canvas mail bag. The insects under less severe conditions 
were all killed. The gas had practically no effect upon the dried 
spores, although it penetrated in sufficient quantity to kill all the 
pyocyaneus, despite the fact that some of the conditions required 
deeper penetration than is ordinarily the case in practical disinfection. 
THE AUTOCLAVE. 
The autoclave evolves the formaldehyd gas by heating formalin, 
mixed with a neutral salt, in a retort under a pressure of at least 45 
pounds to the square inch. 
The ordinary requirement with this form of apparatus in disinfecting 
against bacteria is to use 10 ounces of the formalin solution for each 1,000 
cubic feet of air space with an exposure varying from two to twenty-four 
hours. The United States Quarantine Regulations require a twelve 
hours exposure and 400 c. c., or about 13 ounces per 1,000 cubic feet of 
space. 
It is true that in this process not all the solution put in the retort is 
evaporated, and the amount remaining is noted under each experiment. 
However, there is very little formaldehyd in the residue, for in an 
apparatus evolving gas under pressure, especially if a neutral salt 
glycerin has been added to raise the boiling point, practically all the 
gas passes off with the first half of the liquid. 
No. 8. 
This experiment was done in the room of 2,000 cubic feet previously 
described. (See No. 1.)- Twenty ounces (600 c. c. ) of glyco chloro- 
