27 
EXPERIMENT NO. 5— Continued. 
[4- means growth; — no growth.] 
Organism. 
B . pyocyaneus 
B. typhosus 
B. coli communis . 
B. dysenteric 
B. coli communis . 
B. subtilis 
How exposed. 
Filter paper 
do 
do 
do 
Wilson method. 
do 
Time of exposure in 
minutes, and results. 
5 
10 
20 
30 
40 
60 
+ 
+ 
+ 
- 
- 
- 
• — 
+ 
+ 
+ 
- 
- 
- 
4- 
+ 
— 
- 
- 
- 
4- 
4- 
4- 
— 
- 
- 
4- 
+ 
+ 
+ 
— 
— 
EXPERIMENT NO. 6. 
Formalin-permanganate method. 
Formalin, 600 c. c. 
Permanganate, 300 grams. 
Capacity of room, 2,000 cubic feet. 
Quantity of formaldehyde used per cubic foot, 0.107 gram. 
Quantity of formaldehyde found per cubic foot, 0.04035 gram. 
(Determination made by drawing air from the room, beginning 14 minutes after mixing the 
formalin and permanganate, and consuming 1 hour 10 minutes in the drawing.) 
Yield of formaldehyde, 37.70 per cent. 
Weather: Moderate northwest wind, clear. 
Tempera- 
ture. 
Relative 
humidity. 
Absolute 
humidity 
(grams per 
cubic foot). 
° F. 
Per cent. 
Before mixing HCHO and KMnOi 
71 
45 
3.70 
After 10 minutes 
72 
60 
5.10 
Alter 20 minutes 1 
72 
58 
4.93 
After 2 hours 
72 
55 
4. 68 
See Note, Experiment No. 1. 
[+ means growth; — no growth.] 
Organism. 
How exposed. 
Time of exposure in min- 
utes, and results. 
5 
10 
4 
20 
45 
60 
90 
120 
B. coli communis 
Glass 
+ 
4- 
4- 
B. pyocyaneus 
Filter paper 
4- 
4- 
4- 
4- 
B. typhosus 
do 
+ 
4- 
4- 
4- 
B. coli communis 
do 
+ 
4- 
4- 
4- 
4- 
B. dysenteric 
do 
+ 
4- 
4- 
4- 
B. coli communis 
Wilson method 
4- 
4- 
4- 
4- 
4- 
4- 
B. subtilis . .. 
do 
4- 
4- 
4- 
4- 
4- 
4- 
4- 
The preceding experiment (No. 6^L shows the effects of a relatively 
low humidity upon the germicidal power of the formaldehyde. 
Although the temperature in this experiment was comparatively high 
the time required to kill was much prolonged as compared with the 
experiments in which the temperature and humidity were both high. 
