41 
With comparatively high temperatures, say, 75° F., the yield of 
formaldehyde gas by this method was appreciably higher than by the 
autoclave method, although the time required to exhaust the appa- 
ratus was more than twice as long in the former than in the latter. 
Because of this longer time there was naturally more loss by leakage 
in the retort method before beginning to draw air. The higher per- 
centage would be expected, since in the retort the formaldel^de is not 
subjected to so high a temperature and pressure as in the autoclave. 
Experiment II c shows the loss by leakage after the room in ex- 
periment II had been left closed 72 hours. Although the yield was 
greater in the retort than by an} r other method tried, there arises the 
question, What becomes of the rest of the formaldehyde? This 
point is an interesting one and worthy of further investigation, but 
will not be taken up in this work except in so far as a reduction in 
temperature affects the percentage of formaldehyde obtained. This 
reduction is shown in experiment III (temperature 40° F.,) in which 
only 18.4 per cent wasobtained as against 46.12 per cent in experiment 
II (temperature 73° F.) 
A slightly lower temperature with this method seems necessary to 
produce the same appearance in the room that is observed in the undi- 
luted formalin-permanganate method; that is, about 55° F. with this 
method as against 60° to 65° F. with the method referred to. Even 
then the deposit of paraform is not so marked as with the undiluted 
formalin-permanganate method. The reason for this is not apparent, 
since the percentages obtained with the two methods showed about 
the same relative decrease. 
The quantity of paraform deposited in the room is about the same 
with this method as with the diluted formalin-permanganate and 
autoclave methods. 
Germicidal properties . — As it took approximately 1 hour to exhaust 
the quantity of formalin used in these experiments, the organ- 
isms were not exposed to the action of the formaldehyde until this 
process was completed. The organisms were prepared and ex- 
posed in the usual manner previously described. 
