Ill 
Per cent. 
Retort without pressure 47. 0 
Autoclave 41.5 
Formalin-permanganate 39. 15 
Diluted formalin-permanganate 35. 1 
Sheet spraying 30. 48 
Formalin-aluminum sulphate-lime 14. 0 
The above figures simply represent the percentage of formalde- 
hyde gas found, as compared with the quantity contained in the 
amount of formalin used in an experiment. 
As alcohol is used in the generating lamp, it is impracticable at this 
time to compare the percentage of formaldehyde evolved by this method 
with that evolved by the above methods. 
Under conditions as given above the methods may be arranged 
according to the maximum quantity of formaldehyde gas actually 
found per cubic foot of air space in the room, as follows: 
Grams. 
Retort without pressure _ 0. 05037 
Autoclave 0. 04448 
Formalin-permanganate 0. 0419 
Diluted formalin-permanganate 0. 03755 
Sheet spraying 0. 03262 
Formalin-aluminum sulphate-lime 0. 01498 
Below a temperature of about 65° F. for the formalin-permanganate 
and about 60° F. for the other methods polymerization or other 
change in the formaldehyde takes place to such an extent that only a 
relatively small percentage of gas is obtained. This of course is 
more marked the lower the temperature . a 
The different methods are affected in about the same proportion 
except in case of the sheet-spraying method. In this latter method it 
seems that the formaldehyde is not even given off when the tempera- 
ture is below the point above stated. In the different experiments in 
the bottle with the formalin-permanganate method the percentages 
of formaldehyde liberated agree fairly well, but are slightly lower 
than in the room experiments under similar conditions of tempera- 
ture. The difference is due in all probability to the small quantities 
of substances used in the former experiments. 
The bottle experiments show that a low temperature does not mate- 
rially affect the quantity of formaldehyde actually given off, and 
therefore the small percentages obtained in the room under this con- 
dition are principally due to the formaldehyde undergoing change 
after liberation. 
a This polymerization, however, does not take place in the gas, as evolved by the for- 
maldehyde generating lamp, the product of which does not seem to polymerize under any 
conditions of temperature at which experiments have, up to this time, been conducted. — 
[Ed.] 
32507— No. 27 — 06 — —8 
