36 
EXPERIMENT NO. 14— Continued. 
[+ means growth, — no growth.] 
Organism. 
B . pyocyaneus . . . 
B. coli communis. 
B. dysenteric 
B. subtilis 
B. coli communis . 
B. subtilis 
How exposed. 
Filter paper 
do 
do 
do 
Wilson method. 
do 
Time of exposure in min- 
utes, and results. 
5 
10 
15 
30 
60 
120 
+ 
+ 
+ 
+ 
+ 
- 
- 
+ 
+ 
- 
- 
+ 
+ 
+ 
+ 
— 
— 
The organisms were killed in the above experiment in about the 
same time as in those with the undiluted formalin-permanganate 
method under similar conditions of temperature and humidity. 
The following two experiments (Nos. 14a and 14b), which were done 
after the room in experiment No. 14 had been left closed 4 and 24 
hours, respectively, show how the percentage of formaldehyde became 
reduced by standing. 
Although only 9.6 per cent of formaldehyde was found in experi- 
ment No. 14b, the organisms were killed within a comparatively 
short time. This demonstrates what a small percentage of formalde- 
hyde will kill when the temperature and humidity are high. Under 
these conditions the principal effect of a limited reduction in the per- 
centage of formaldehyde seems to be in decreasing penetration, as 
shown by results with exposures by the Wilson method. 
EXPERIMENT NO. 14a. 
After the room in experiment No. 14 had been left closed 4 hours. 
Quantity of formaldehyde found per cubic foot, 0.02276 gram. 
Yield of formaldehyde, 21.27 per cent. 
Weather: Very gentle breeze during intervening 4 hours. 
Temperature of room during experiment, 87° F. 
Relative humidity, 79 per cent. 
Absolute humidity, 10.69 grams per cubic foot. 
[+ means growth; — no growth.] 
Organism. 
B. pyocyaneus 
B. coli communis . 
B. dysenteric 
B . subtilis 
B. coli communis . 
B. subtilis. 
How exposed. 
Filter paper 
do 
do 
do 
Wilson method . 
do 
Time of exposure in minutes, 
and results. 
+ 
+ 
+ 
10 25 30 45 ‘ 60 120 
+ 
+ 
+ 
