THE BREATH OF LIFE. 
93 
a certain quantity of tlie vivifying principle of tlie atmosphere, 
diminishing the amount of oxygen present and available 
for other purposes, but it likewise communicates to the air 
an equal volume of another gas — carbonic acid, — a substance 
possessing the most deadly properties — the pure gas suffo- 
cating animals placed in it as if they had been plunged into 
so much water. Even when it is present in the air in only 
small quantities, it produces very deleterious effects, 4 per 
cent, acting like a narcotic poison in the atmosphere, and 
even a less proportion producing depressing- effects of a most 
injurious description. If, then, a candle which consumes so 
small a quantity of oxygen causes such a change in the atmo- 
sphere, how much more will the respiration of human beings 
tend to vitiate it. It has been calculated that a man every 
twenty-four hours consumes nearly 400 cubic feet of air, with 
evolution of the deleterious carbonic acid gas ; and that were he 
to be enclosed for twenty-four hours in a room eight feet square 
by nine feet high, he would be moribund at the end of the 
time. And these are not merely fanciful or supposititious cases. 
The action of contaminated confined air upon the health of the 
inhaler is one of the most potent and insidious causes of disease. 
Any addition to the natural atmosphere that we breathe must 
be a deterioration, and absolutely noxious in a greater or less 
degree. Our health, says Thackrah, would immediately suffer 
did not some vital conservative principle accommodate our 
functions to circumstance and situation. But this seems to get 
weaker from exertion. The more we draw on it, the less balance 
it leaves in our favour. The vis vitae, which, in a more natural 
state, would carry the body to seventy or eighty years, is pre- 
maturely exhausted, and, like the gnomon shadow, whose 
motion no eye can perceive, but whose arrival at a certain point 
at a definite time is inevitable, the latent malaria, which, year 
after year, seems to inflict no perceptible injury, is yet hurrying 
the bulk of mankind with undeviating, silent, accelerating 
rapidity to a premature grave. Pure air is the food designed 
by nature for the constitution. Man subsists upon it more than 
upon his meat and drink ; and there are numberless instances 
of persons living for months and years on a very scanty supply 
of aliment ; but no one can subsist even for a few minutes with- 
out a copious supply of the aerial element. 
Deaths from the respiration of many persons in a confined 
space are, unhappily, not rare ; and without going back to the 
shocking instance of the Black Hole at Calcutta, we may refer 
to an equally lamentable occurrence which happened a few years 
ago in an emigrant ship, in which, during a storm off the 
English coast, the emigrants were confined below. In less than 
six hours more than sixty persons perished ! 
