76 
These results indicate that a reduction in percentage of formalde- 
hyde diminishes its killing power proportionately more for spore 
bearing than nonspore-bearing organisms. 
An experiment was performed in which the moisture was absorbed 
by 1 hour exposure of calcium chloride, after which no moisture was 
introduced. B. coli communis and B. subtilis exposed for 24 hours 
under these conditions grew as well when planted in boullion as did 
the controls. The temperature at time of exposing the organisms in 
this experiment was 83° F. 
In another experiment, in which the bottle was charged with for- 
malin 1 c. c. and permanganate 0.5 gram and dried 1 hour with cal- 
cium chloride, slips of filter paper were moistened with an emulsion of 
B. coli communis and B. subtilis, respectively, and exposed while the 
slips were still in a very moist condition. B. coli communis was killed 
within 10 minutes and B. subtilis within 30 minutes. This simply 
shows that in the presence of the moisture on the slips the formal- 
dehyde exerted a germicidal action. 
In order to demonstrate the influence of cold upon the germicidal 
properties of formaldehyde, a number of experiments were conducted 
at or below a temperature of 60° F. Different percentages of hu- 
midity were also used. 
The method of setting off the formalin and permanganate, the dry- 
ing by calcium chloride, and the introduction of the moisture have 
been described (p. 66). 
A summary of conditions and results are given in the following table : 
TABLE 12. 
Experiments in a fy-liter bottle; formalin-permanganate method. 
Formalin 1 c. c., permanganate 0.5 gram. 
Moisture removed by calcium chloride. 
Varying quantities of moisture introduced. 
Temperature at or below 60° F. 
B. coli communis and spores of B. subtilis exposed on filter paper. 
[4- means growth, — no growth.] 
Results with B. coli communis, and time 
of exposure in minutes. 
Tem- 
pera- 
Rela- 
tive 
hu- 
Results with spores of B. subtilis, and 
time of exposure in minutes. 
ture. 
mid- 
5 
10 
15 
20 
30 
45 
60 
75 
90 
120 
ity. 
5 
10 
15 
20 
30 
45 
60 
75 
90 
120 
° F. 
Per c- 
+ 
+ 
60 
8 L 
4- 
+ 
+ 
+ 
f 
+ 
+ 
— 
- 
— 
+ 
+ 
60 
8i 
-f • 
+ 
4- 
+ 
+ 
+ 
+ 
4- 
- 
- 
+ 
+ 
- 
- 
— 
- 
— 
— 
- 
60 
83 
, 
•4- 
-f. 
+ 
+ 
4- 
+ 
4- 
- 
- 
4 - 
4 - 
60 
6 ' 
+ 
4- 
4- 
•4- 
+ 
+ 
+ 
4- 
+ 
60 
64 
4- 
+ 
4- 
+ 
-p 
4- 
4- 
+ 
4- 
.... 
+ 
+ 
+ 
60 
53 
+ 
4- 
+ 
+ 
+ 
+ 
4- 
4- 
4- 
4- 
+ 
+ 
+ 
+ 
+ 
60 
53 
-i- 
+ 
+ 
+ 
+ 
+ 
4- 
4- 
4- 
4- 
+ 
+ 
+ 
4- 
+ 
+ 
— 
- 
- 
- 
60 
50 
+ 
+ 
+ 
+ 
+ 
4- 
+ 
4- 
4- 
4- 
+ 
+ 
4- 
+ 
+ 
+ 
— 
- 
- 
- 
53 
54 
+ 
+ 
+ 
+ 
+ 
4- 
4- 
4- 
4- 
4- 
+ 
+ 
.+ 
+ 
+ 
+ 
- 
- 
- 
- 
50 
81 
+ 
+ 
+ 
+ 
+ 
4- 
4- 
4- 
4- 
4- 
+ 
+ 
4- 
+ 
4- 
+ 
— 
- 
- 
- 
50 
89 
+ 
+ 
4- 
+ 
+ 
4- 
4- 
+ 
+ 
— 
+ 
+ 
4- 
+ 
+ 
+ 
+ 
- 
- 
- 
46 
95 
. 
+ 
+ 
+ 
+ 
4- 
+ 
4- 
4- 
4- 
+ 
+ 
4- 
+ 
+ 
+ 
+ 
+ 
— 
— 
40 
95 
4 - 
tl 
+ 
+ 
+ 
+ 
4- 
4- 
+ 
+ 
