6 
ury Department of-tlie United States, are cholera, yellow fever, typhus 
fever, smallpox, plague, and leprosy. To these, from a municipal or 
sanitary standpoint, may be added the eruptive fevers, measles, chicken 
pox, scarlet fever, and the dread scorge of municipalities — diphtheria. 
Leprosy for the present is left out of consideration, for while its causa- 
tive organism is known its method of contagion or infection is as yet 
unsettled. 
An effort has been made in the experiments that are about to be 
detailed to establish several points: First, the efficiency of sulphur 
dioxide as a disinfectant ; second, the minimum percentage necessary 
for efficient disinfection against yellow fever, diphtheria, cholera, and 
plague; third, to demonstrate the minimum exposure to this minimum 
percentage in order that disinfection of vessels may be reduced to the 
smallest possible basis of expense, damage, and loss of time. 
Ever since the systematic employment of suli^hur dioxide as a germi- 
cidal agent it has been empirically recommended that moisture should 
be present and should be hupplied either by the introduction of steam 
or water in the form of spray, or by water vaporized by the heat engen 
dered in the combustion of the suliffiur employed for the production of 
the disinfecting agent. This matter has been the subject of much dis- 
cussion, and while generally recognized as being necessary for efficient 
work, there have been but few authoritative statements on the subject. 
Therefore, the first experiment made was with a view of solving this 
question. This was done after the following manner : 
PEELOIIXARY EXPERIMENT. 
A large bell jar having an aperture for the admission of the gas was 
loaded with envelopes containing strips of flannel which were wet with 
bouillon cultures of anthrax, cholera, the colon bacillus, typhoid, diph- 
theria, the bacillus icteroides of Sanarelli, and the bacillus of bubonic 
plague. The envelopes were sealed and were then perforated with a 
punch to admit the access of the gas. The bell jar was mounted on 
a plate of ground glass and air-tight contact was obtained by the use 
of vaseline. Licpiefied sulphur dioxide was the agent employed, and in 
order to insure its reaching the bell jar in a state of thorough dryness 
the gas was passed through two drying columns containing pumice 
stone wet with strong sulphuric acid. The percentage of sulphur 
dioxide contained in the atmosphere of the bell jar was determined at 
once by means of the decolorizing action of the gas upon a decinormal 
solution of iodine and was again determined at the co.nclusion of the 
time of exposure. The first experiment showed the presence of 9.8 per 
cent of dry sulphur dioxide, practically the 10 per cent demanded by 
the quarantine regulations of the Treasury Department. The time of 
exposure was forty-eight hours. At the conclusion of the experiment 
the quantity of gas in the atmosphere had fallen to about 9.2 per cent, 
showing practically that during the whole duration of the experiment 
