The report of the British Parliament Commission gives the following data
in this important question: "The amount of carbonic acid in the air is
about 1/2000 or .0005; the amount expired is about 1/12, or .083. Respired
air contains 1/10 or 1 of carbonic acid, and this must be diluted ten
times to make the air safe. Thus, 1/10 / 10/1 = 1/100, or .01; and this
again divided by 10, or 1/100 / 10/1 = 1/1000 or .001, gives the amount of
ventilation needed to reduce the air to that state of purity that only
1/1000 more of carbonic acid should be added to the air, when it would be
represented by .0015 instead of .0005."
Observing this rule, and taking 300 cubic feet as the air respired for the
24 hours, to dilute it ten times it must be mixed with ten times the bulk,
or 3000 cubic feet--the space to be allowed for each individual; but if it
is wished to keep up a pure air, it must be mixed with ten times this bulk
again, or 30,000 cubic feet, which shows the ventilation needed to
maintain an atmosphere nearly pure; or there must be admitted into the
space of 3000 cubic feet nearly 21 cubic feet per minute of fresh air by
ventilation, if the man in it is to breathe an atmosphere which shall
contain only three times more of carbonic acid than the air he breathes
originally contained; or again, 300 cubic feet, 3000, and 30,000, mark the
requirements of one individual, in 24 hours, for respiration, space, and
ventilation. On a calm day, when there were no strong breezes to change
the air of the stockade, the entire quantity of air in the old stockade,
allowing the palisades to be on the average 20 feet high, could be
exhausted in 20 minutes by the 30,000 men respiring 300 cubic inches per
minute. This is not a proper estimate to offer; but it will give a just
idea of the rapid and fearful vitiation of the air that took place within
the enclosure.
Vierodt shows how rapidly carbonic acid increases when foul air is
breathed, and Lehman proves the rapid disengagement of the gas in moist
atmospheres.
Symptoms of uneasiness manifest themselves when the air contains from
6/1000 to 7/1000 carbonic acid, and when the proportion amounts to ten
parts to 100 of air, death ensues. "This effect is visible upon vegetables
also, and many of them are extremely susceptible of impurities in the air,
and very slight modifications in the proportion of its constituents are
more or less prejudicial to their growth." But plants, like animals, vary
in regard to the delicacy of their constitutions, some being much more
susceptible than others.
In warm climes the respiration becomes slower, and in consequence there
is less of carbon burned and less oxygen absorbed; but on the other hand
the functions of the skin become vastly increased, the bilious secretions
become more active, and the excess of carbon is eliminated by this
channel.
That we expire more carbonic acid in a warm, moist atmosphere, and less in
a cold, dry climate, is shown by the exhilaration of our spirits on a fine
frosty morning.
No wonder that men lost their reason in this prison, for the blood no
longer reddened from the imperfect arterialization, and burdened the brain
with its effete matter, paralyzing and clogging up the delicate filaments
and the narrow channels of thought and life.
We have seen that the blood is subject to incessant variations in its
precise chemical constitution; a free atmosphere, well supplied,
oxygenates and destroys the numerous impurities that tend to lurk in the
system and develop disease.
Bichat shows, in his researches on life and death, how the black and
carbonized blood disturbs the functions of the brain and acts like a
narcotic poison, causing the heart finally to cease its throbbings.
These miasms and poisons floated about the enclosure where there was not
the least sign of vegetable organism to absorb and convert them. As they
passed into the systems of the prisoners they became the cause of disease,
decrepitude, and death.