45 
EXPERIMENT NO. 21a. 
After the room in experiment No. 21 had been left closed 72 hours ( 8 days). 
Quantity of formaldehyde found per cubic foot, 0.00637 gram. 
Yield of formaldehyde, 5.95 per cent. 
Weather: Rather strong wind during the 3 days; rained several times. 
Temperature of room during experiment, 75° F. 
Relative humidity, 78 per cent. 
Absolute humidity, 7.30 grams per cubic foot. 
[4- means growth; — no growth]. 
Organism. 
How exposed. 
Time of exposure in min- 
utes, and results. 
5 
10 
20 
30 
60 
120 
B pyocyaneus 
Filter paper 
+ 
+ 
4- 
+ 
B coli communis 
do 
+ 
+ 
+ 
+ 


R . d.ysent.erisp. 
do 
4- 
4- 
4- 
B, subtilis 
do 
+ 
+ 
4- 
4- 
+ 
+ 
B. coli communis 
Wilson method 
4- 
+ 
+ 
4- 
4- 
4- 
B . subtilis 
do 
+ 
4- 
4- 
+ 
+ 
4- 
The following experiment (No. 22) was done at a comparatively 
low temperature, in consequence of which the percentage of formalde- 
hyde gas obtained was small. The same hazy appearance of the air 
in the room was observed as with the previous methods under similar 
conditions of temperature. The deposit of paraform was not so 
marked as with the undiluted formalin-permanganate method, but 
about the same as with the diluted method. 
Considering the difference in temperature, the germicidal action of 
the formaldehyde in this experiment is better than in experiment 
No. 8 with the formalin-permanganate method. 
EXPERIMENT NO. 22. 
Retort without pressure 
Formalin, 600 c. c.; glycerin, 6 c. c. 
Capacity of room, 2,000 cubic feet. 
Quantity of formaldehyde used per cubic foot, 0.107 gram. 
Time required to exhaust material in retort, 1 hour and 10 minutes.. 
Quantity of formaldehyde found per cubic foot, 0.01982 gram. 
(Determination made by drawing air from room, beginning 15 minutes after exhausting retort 
and consuming 1 hour and 20 minutes in the c rawing) . 
Yield of formaldehyde, 18.4 per cent. 
Air in room had a very hazy appearance diming the experiment, probably due to polymeriza- 
tion of formaldehyde. 
Weather: Clear and cold; light northeast wind. 
Tempera- 
ture. 
Relative 
humidity. 
Absolute 
humidity 
(grams per 
cubic foot) . 
Before beginning to introduce the gas 
o Jr. 
40 
42 
Per cent. 
52 
69 
1.47 
2.11 
After 1 hour 
See Note, Experiment No. 18. 
