102 
EXPERIMENT No. 64. 
Retort without pressure; formalin 2,000 c. c. 
The process of vaporizing the formalin was continued for 2 hours, at the end of which time about 
300 c. c. of fluid remained in the retort. During this time the retort was changed from one end 
of car to the other every 15 minutes. 
Weather: Cloudy, melting snow, no wind. 
Temperature in car at beginning of experiment, 52° F. 
Relative humidity in car at beginning of experiment, 40 per cent. 
Time of exposure, 2 hours, from time of beginning tb introduce the gas (12 m. to 2 p. m.). 
Temperature in car after opening and airing 15 minutes, 52° F. 
Relative humidity in car after opening and airing 15 minutes, 40 per cent. 
[ + means growth; — , no growth.] 
Organism. 
Place of exposure in car. 
Result. 
B. coli communis 
B. diphtherise 
B. typhosus 
B. subtilis 
Toilet room 
Drawing room 
Floor, main sleeping compartment 
Berth, upper No. 4 
Berth, lower No.8 
Floor, main sleeping compartment 
Berth, upper No. 10 
Berth, lower No. 6 
Toilet room 
Drawing room 
Floor, main sleeping compartment 
Berth, upper No. 6 
Berth, lower No. 4 
Drawing room 
Floor, main sleeping compartment 
Berth, upper No. 6 
+ 
+ 
+ 
+ 
+ 
+ 
+ 
+ 
+ 
+ 
+ 
+ 
+ 
With this method all the guinea pigs showed lesions of tuberculosis, 
one in experiment Xo 62 dying before the control. The others only 
showed a diminished virulence of the organism. Otherwise the results 
obtained in the above experiments agree rather closely with those in 
the formalin-permanganate method under similar conditions of tem- 
perature and humidity. 
As much of the 2 hours is consumed in introducing the formalde- 
hyde gas, doubtless more advantage would be gained by a longer 
exposure with this method than would be the case with the formalin- 
permanganate method. Although the temperature was 73° F., and 
humidity- 57 per cent in experiment No. 63, the latter was not high 
enough to give efficient results. This indicates that about the same 
percentage of humidity is required in this method as in the forma lm- 
permanganate method. 
IV. AUTOCLAVE UNDER PRESSURE. 
About 20 minutes were required to raise the pressure in the auto- 
clave to 60 pounds. The pressure was kept between 40 and 60 
pounds while vaporizing the formalin. This process required from 
40 to 60 minutes in the different experiments, after which practically 
no liquid remained in the autoclave. 
