109 
EXPERIMENT NO. 71. 
Two generating lamps; commercial wood alchool 3,000 c. c. (1,500 c. c. in each lamp). 
Lamps placed one in each end of main sleeping compartment of car. 
Weather: Cloudy, moderate northeast wind. 
Temperature of car at beginning of experiment, 50° F. 
Relative humidity of car at beginning of experiment, 55 per cent. 
Time of exposure, 2 hours (12.30 p. m. to 2.30 p. m.) . from time of starting lamps and closing car. 
Temperature in car after opening and airing 10 minutes, 45 ° F. 
Relative humidity in car after opening and airing 10 minutes, 57 per cent. 
[ + means growth, — no growth.] 
Organism. 
Place of exposure in car. 
R mb'. r.nm, m, unis 
Toilet room 
R diphtheria 1 . 
Smoking room 
Drawing-room 
Floor main sleeping compartment 
Berth, lower No. 10 
Toilet room 
B. typhosus 
Smoking room 
Berth, upper No. 10 
Toilet room 
B. subtilis 
Smoking room 
Floor main sleeping compartment 
Berth, upper No. 2 
Berth, lower No. 6 
Toilet room 
Smoking room 
Floor main sleeping compartment 
Berth, upper No. 8 
Result. 
+ 
4 - 
+ 
+' 
+ 
+ 
+ 
+ 
+ 
+ 
4 - 
+ 
+ 
+ 
+ 
The results in experiment No. 68 are satisfactory except that the 
tubercle bacilli were not killed, although their virulence was dimin- 
ished. In the other experiments most of the organisms escaped 
destruction, due no doubt to the low relative humidity and tempera- 
ture. 
In all the experiments with this method it was possible to enter the 
car almost as soon as it was opened. Consequently, no special ad- 
vantage would likely have been gained by a longer exposure in the 
above experiments. Although this method increased the humidity 
considerably, it did not do so sufficiently in experiment No. 69 
(humidity 58 per cent) to accomplish efficient results. 
SUMMARY AND CONCLUSIONS. 
Formaldehyde gas, regardless of the method by which it is evolved, 
is a powerful surface disinfectant under certain conditions. Success- 
ful disinfection with it is so dependent upon several factors that its 
usefulness is more or less limited. The temperature and humidity 
are of primary importance, while the influence of the winds, character 
of the room, etc., are of secondary importance. 
