10 
sulplinr. This method is efficient and rapid, but very expensive, and, 
except under certain conditions, may be eliminated from our considera- 
tion of practical quarantine measures. Neither is it worth while, in 
this connection, to give consideration to either of the other two methods 
of the treatment of either sulphur or copper by sulphuric acid, as they 
entail the use of heat and apparatus more or less complicated. In 
addition to which, it is a procedure not free from danger for the unin- 
itiated to subject concentrated sulphuric acid to the action of heat. 
Terrific accidents and horrible burns might easily result. But a means 
easy and effectual still remains to us. That is the combustion of sul- 
phur in the presence of atmospheric oxygen. 
Taking into consideration the actual weight of a given number of 
cubic inches of sulphur dioxide, we find that disregarding temperature 
and barometric pressure, and presuming that our sulphur is free from 
contaminations or impurities, we can obtain about 1.15 per cent of sul- 
phur dioxide by the combustion of 1 pound of sulphur in a space of 
1,000 cubic feet. Sulphur, however, is seldom pure, containing impu- 
rities in the nature of sulj)hate of lime and sand, and a portion of it 
being always oxidized to the formation of ill-defined compounds. 
Again, all gases have a very regular rate of expansion and a constant 
factor is equivalent to ^-g-o for each degree centigrade from zero up. 
It has been noted by Surgeon Carter, M. H. S., that the holds of vessels 
during the process of combustion of sulphur sometime reaches 140° P., 
or 60° C. Presuming, therefore, on a normal temperature of 22° C. we 
have ranges of temperature from 22° to 60° C., or a range of 38°, giving 
an expansion of gas about equivalent to of the entire mass. Taking 
this, we have 1.03 as the obtainable percentage under normal condi- 
tions of temperature, and making allowance for the impurities noted 
as existing in sulphur, it might be said that in round numbers 101 
pounds of sulphur can be counted on as producing 10 per cent sulphur 
dioxide in 1,000 cubic feet of space. To obtain 5 per cent, therefore, 
is simply to use one-half or 51 pounds. Of course, it would be prudent 
to allow for wastage or for imperfect combustion, and these factors one 
must decide for himself. It has been suggested that 20 per cent be’ 
allowed for these sources of error. 
As has been seen, the presence of moisture is necessary to an effectual 
germicidal power on the part of sulphur dioxide. In other words, that 
sulphur dioxide must be converted into sulphurous acid. It is compara- 
tively easy to arrive at the amount of water necessary for this. The 
atomic weight of sulphur dioxide as compared with sulphurous acid is 
as 64 to 82 ; in other words, about 20 per cent o-f the weight of sulphur 
used should be allowed for water to be volatilized or added to produce 
a proper hydration. Therefore, one-fifth pound, theoretically, of water 
should be volatilized or added for each pound of sulphur burned. Many 
ways suggest themselves of effecting this result. The water might be 
ai^plied in the form of steam after the combustion of the sulphur. It 
