11 
In Laboratory Bulletin No. 8. on ‘‘Sulphur dioxide as a germicidal 
agent,'* Geddi ngs found that 4.25 }>er cent of that gas for twenty-four 
hours’ time invariabU^ kills the bacillus pestis on the surface. 
M}' own work with formaldehyde (soon to be published) shows that 
the plague organism is as susceptible to this germicidal agent as other 
non-sporebearing organisms. Aiyv of the standard methods for 
evolving the free formaldehyde gas are applicable. 
As far as practical disinfection for plague is concerned, it may be 
mentioned here that sulphur dioxide is probably a much more useful 
agent for use in ships, stores, houses, and dwellings infested with 
vermin, because it is destructive to the higher forms of animal life, 
whereas formaldehyde fails to kill mammals and insects with the 
same certainty that it kills microbes. In combating plague it is very 
important to kill the fleas, rats, mice, and other forms of animal life 
capable of carrying the infection. Sulphur has this j)ower, which 
formaldehyde totally lacks. 
CHEMICAL DISINFECTANTS FOR THE PLAGUE BACILLUS. 
The bacillus of plague shows no special peculiarity in its relation to 
chemical disinfectants in solution. We have found the following ordi- 
nary disinfectants to have very marked aseptic powers. 
ASolutiom u'hicJi prevent the growth of the baeilhifi pestis. 
Bichloride of mercury and hydrocloric acid 
Bichloride of mercury 
Formalin i 
Carbolic acid (pure ) 
The following tablo gives the results of the German plague commis- 
sion upon the power of disinfecting agents in relation to the bacillus 
pestis : 
1 to 50, 000 
1 to 25, 000 
1 to 25, 0(X1 
1 to 830 
Agent. 
Xiunber of miiiute.s nec- 
essary. 
Carbolic acid: 
5 per cent 
1 per cent 
Lysol : 
2.5 percent 
1 per cent 
Sublimate, 1 to 1,000 
Chloride of lime, I to 1,000 
(iui/>klime 
Milk of lime mixed with equal ipmntity of .sail 
Black soap: 
1 per cent * 
3 per cent 
Sulphuric acid, 1 to 2,000 
Hydrochloric acid, 1 to 1,000 .1 
1 
10 
1 
5 
Immediate destruction. 
If. 
30 
tX) 
More than an hour. 
:in minutes. 
5 
30 
