55 
EXPERIMENT NO. 30 a. 
After the room in experiment No. 30 had been left closed 24 hours. 
Quantity of formaldehyde found per cubic foot, 0.02225 gram. 
Yield of formaldehyde, 20.80 per cent. 
Weather: No wind. 
Temperature, 72° F. 
Relative humidity, 91 per cent. 
Absolute humidity, 8.51 per cubic feet. 
The exposed organisms were killed in the above experiments in a 
comparatively short time, but hardly as short as in the previous 
methods under similar conditions of temperature and humidity. 
Experiment No. 30 a was tried after the room in experiment No. 30 
had been left closed 24 hours. It shows that in a well-closed room 
like the one used by us the percentage of formaldehyde gas in the room 
was still comparatively high after 24 hours’ standing and that the 
exposed organisms were killed then in about the same time that they 
were 1 hour after spraying the sheets. 
The following experiment (No. 31) shows the inefficiency of this 
method for disinfection purposes during cold weather, temperature 
43.5° F. In this experiment even the nonspore-bearing organisms 
were not killed within 3 hours and only 3.16 per cent of formaldehyde 
was found. 
EXPERIMENT NO. 31. 
Sheet spraying. 
Formalin, 600 c. c. 
Capacity of room, 2,000 cubic feet. 
Quantity of formaldeyhde used per cubic foot, 0.107 gram. 
Quantity of formaldehyde found per cubic foot, 0.00345 gram. 
(Determinations made by drawing air from room beginning 1 hour 30 minutes after spraying 
sheets and consuming 1 hour 15 minutes in the drawing.) 
Yield of formaldehyde, 3.16 per cent. 
Condition of weather: Clear and dry, light southwesterly breeze. 
Tempera- 
ture. 
Relative 
humidity. 
Absolute 
humidity 
(grams per 
cubic foot). 
Before spraying 
° F. 
43.5 
Per cent. 
52 
1.67 
1 hour after 
43.0 
55 
1.74 
3 hours after 
50.0 
61 
2.48 
Organisms not exposed until 1 hour after spraying sheets. 
