10

     Both objects were attained. Bundles of clothes wrapped fairly tightly up
were thoroughly penetrated by the gas. A consideration of the tables will show
this. For example, in Experiment I the gas penetrated through four bags,
—three of coarse blanket and one of cotton, killing 10 fleas out of 11 placed
centrally. It penetrated through three bags, two of blanket and one of cotton
killing all the fleas placed centrally. The gas was led direct from flasks outside
the room without the use of a fan. About two cubic feet of gas were introduced
into the above described room of 830 cubic feet capacity and the time of exposure
was 51 minutes.

     Experiment II shows the same condition of affairs as Experiment I, but
a shorter exposure of 30 minutes with not so successful a result.

     The most successful experiment is No. III. About 4.38 cubic feet of gas
were pumped into the room by a fan for 20 minutes and then the delivery of gas
was stopped. The gas was distributed by nine small tubes throughout the
room. The fleas in all parts of the room were killed, even though the tubes con-
taining them were wrapped up in several layers of thick sheeting and blanket.
But in series 3 where they were surrounded by a durree, blanket, and coat very
tightly rolled, eight fleas remained alive out of nine. Fleas put in cages with bran
and sand at the bottom were all killed in this experiment, showing that there
is a certain penetration of the gas into these substances,—an important point in
the disinfection of houses, as the fleas bury themselves in dust, grain, etc.

     If clothes are left loosely in boxes, can we say the gas will penetrate suffi-
ciently to kill? If so, it would obviate the necessity of hanging out the clothes
for disinfection.

     Experiments IV and V were tried to determine this point. If pipes were
led with great care into the boxes, fleas were killed. But it will be noted that
failure occurred in some instances, where, perhaps, owing to the tube being
kinked, some obstruction to the entrance of the gas occurred. It is much
safer to hang up the clothes on pegs or scatter them loosely about the room.

     In Experiment IV it is noted that the room was entered in 30 minutes from
the commencement of the operations. The disinfection of the clothes was very
thorough, so that it is possible by pumping gas into a room to kill fleas in clothes
and deliver clothes back to their owners in thirty minutes. The use of the test
rod mentioned on page 6 enables one to enter the room with safety.

     (b) Second method.—The fan and pipes are, however, a complicated and
expensive means of distributing the gas. Accordingly the method of producing
the gas, as detailed on pages 5 and 6, was tried.

     A flea-tight and very air-tight godown—one of those used in the Plague
Commission's experiments—was taken. Its cubic capacity is about 346 cubic
feet. Into a small china vessel 4 ozs. of water were put, 2 ozs. of commercial