any length of time. Some revived after an hour's immersion; others,
after two or three hours--the revival being slow in proportion to the
time of exposure to the gas. Somewhat similar results were obtained
with flies and bees in hydrogen and azote. To try the effect of
deprivation, a fly was shut up in a tube with but a small quantity of
common air, on the 5th February, in a temperature varying from 52° to
60° during the whole time of the experiment. The insect manifested no
uneasiness until the 25th day, and was found dead on the 28th. Another
fly, enclosed in a similar tube, with a quantity of air not more than
a few times its own volume, became languid on the second day, and
motionless on the twelfth, but revived on being taken out.

Flies immersed in oxygen were found dead the second day, with a
diminution of the quantity of the gas. Coal-gas produced almost
immediate insensibility, with a few feeble attempts at revival, but in
no case effectual. Sulphuretted hydrogen also proved especially
fatal--an instant's immersion was sufficient to destroy life; though
withdrawn at once, not one of the flies recovered. It was the same
when the portion of gas diffused in the air of the tube was so minute
as to be scarcely appreciable. On bees, too, the effect was similar;
the deadly nature of the gas on their delicate organisation being
invariably destructive. Like results were obtained with chlorine.

In the class of vapours, ammonia proved fatal in one case, and
harmless in another; muriatic acid stupified in two, and killed in
twenty-four hours. The vapour of nitric acid was equally fatal with
sulphuretted hydrogen; and, in alcoholic vapour, at a temperature of
74°, 'for a few minutes the fly shewed increased activity; in a few
more, it became nearly motionless; after about a quarter of an hour,
it appeared to be torpid. Now, exposed to the air of the room, in a