Thus it appears how important is the function of respiration, and how
vital the necessity for pure air.
Pure dry air contains about 21 gallons of oxygen, and 79 gallons of
nitrogen out of 100, and about one gallon of carbonic acid out of 2500.
Man will consume, on the average of 20 respirations a minute, or 1200
respirations the hour, about 20 pounds of air, and give off 2-1/2 pounds
or more of carbonic acid, besides half a pound of watery vapor, per diem,
or, according to Andral and Gavaret, 22 quarts of carbonic acid per hour.
We have shown in the chapter on Alimentation how this process of
respiration affects the nutrition, and how serious the results of its
disturbance. The purer the air, the more perfect the type of men and
animals. This was understood by the ancients, and they established their
most famous schools for gladiatorial training at Capua and Ravenna.
The same law is observed at the present day by the admirers of the
race-horse. The purity of the air gives purity to the blood, and the blood
builds up the system in like proportion of excellence.