CHEMISTRY AND PHYSICS. 39 
at the end of the ninth hour. In a third experiment, at sixty-five degrees F., 
the mouse was dead in four hours and forty-two minutes. 
T. H. Dinsmore, jr., also experimented, using mice and kittens confined in 
large jars of oxygen. They were left in thirty to sixty minutes in general, but 
one kitten that was left in an hour and a half was removed in an unconscious 
state. This result was attributed to theaccumulation of carbon dioxide. In the 
other cases no result was observed except an increase in the rate of respiration. 
After remaining in the oxygen an hour they were apparently as well as when 
first placed in the gas. These experiments can hardly be regarded as conclusive 
because of their short duration. 
It should be mentioned further, before taking up a description of our own work, 
that one or two writers do state that animals may live in oxygen without incon- 
venience; but no experimental evidence is adduced on the point. 
In our investigations we designed to experiment with a variety of animals, 
introducing them gradually into the atmosphere of oxygen, and retaining them 
under its influence for a somewhat prolonged period. We also deemed it wise to 
avoid the use of animals which, like mice, cannot endure much handling even 
under normal conditions. The animals were enclosed in a tight wooden box one 
cubic foot in capacity. It hada glass front. An opening at the top for the in- 
troduction of the animals was closed by means of a tin lid which rested ina 
a groove into which melted wax was poured. Openings fitted with glass tubes, 
which could. be closed with rubber stoppers, communicated with tin dishes for 
food and water. Two other openings served to admit oxygen at one of the lower 
corners, and for its exit at the upper diagonally opposite one. The box also con- 
tained a flat tin dish, partially filled with a solution of sodium hydroxide, the 
dish being covered with wire screen. A layer of sawdust was placed in the bot- 
tom of the box. The oxygen used was prepared from a mixture of potassium 
chlorate and manganese dioxide, and was stored for at least a week before use 
in cylinders. The oxygen was delivered from the cylinders, passing through a 
wash-bottle containing water, which served as an index to the rate of supply, 
and thence into the respiration chamber. 
The storage of the gas was for the purpose of affording ample time for the 
absorption of all solids projected over in its preparation, and the gas as delivered 
was perfectly clear, though doubtless not chemically pure. A steady, though 
not very rapid, current of the gas was maintained throughout the continuance 
of each experiment. Sometimes, if the animal seemed oppressed, the current of 
gas was quickened for atime. It was thought that the rate of transmission, with 
the assistance of the sodium hydroxide solution, was sufficient to keep the excre- 
tory gases removed. 
Five experiments were made, and in all but the second the animals were 
watched practically continuously. In the second the watching was continued 
for the first nineteen hours, and after that the time between observations was 
never longer than four hours. 
First Experiment.—In this experiment a grown male cat was confined in the 
respiration chamber at five p. m., April 15, 1899. From the nature of the 
arrangements, observations could be made upon the respiration and general 
behavior only. In this, as in all of the experiments, the animal was put into the 
chamber while it was filled with air, and this was gradually displaced by the 
oxygen. The cat remained in the apparatus until 10:45 o’clock a. m. the next 
day, or nearly thirty hours. The table below is a record of the observations 
made: 
