. The air in the projectile
must, therefore, be renewed. How? By a very simple method, that of
Messrs. Reiset and Regnault, indicated by Michel Ardan during the
discussion of the meeting.

It is known that the air is composed principally of twenty-one parts of
oxygen and seventy-nine parts of azote. Now what happens in the act of
respiration? A very simple phenomenon, Man absorbs the oxygen of the
air, eminently adapted for sustaining life, and throws out the azote
intact. The air breathed out has lost nearly five per cent, of its
oxygen, and then contains a nearly equal volume of carbonic acid, the
definitive product of the combustion of the elements of the blood by the
oxygen breathed in it. It happens, therefore, that in a confined space
and after a certain time all the oxygen of the air is replaced by
carbonic acid, an essentially deleterious gas.

The question was then reduced to this, the azote being conserved
intact--1. To remake the oxygen absorbed; 2. To destroy the carbonic
acid breathed out. Nothing easier to do by means of chlorate of potash
and caustic potash. The former is a salt which appears under the form of
white crystals; when heated to a temperature of 400 deg. it is transformed
into chlorine of potassium, and the oxygen which it contains is given
off freely. Now 18 lbs. of chlorate of potash give 7 lbs of oxygen--that
is to say, the quantity necessary to the travellers for twenty-four
hours.

As to caustic potash, it has a great affinity for carbonic acid mixed in
air, and it is sufficient to shake it in order for it to seize upon the
acid and form bicarbonate of potash. So much for the absorption of
carbonic acid.

By combining these two methods they were certain of giving back to
vitiated air all its life-giving qualities. The two chemists, Messrs.
Reiset and Regnault, had made the experiment with success.

But it must be said the experiment had only been made _in anima vili_.
Whatever its scientific accuracy might be, no one knew how man could
bear it.

Such was the observation made at the meeting where this grave question
was discussed. Michel Ardan meant to leave no doubt about the
possibility of living by means of this artificial air, and he offered to
make the trial before the departure.

But the honour of putting it to the proof was energetically claimed by
J.T. Maston.

"As I am not going with you," said the brave artilleryman, "the least I
can do will be to live in the projectil