4311. Why are persons who live in close rooms and crowded cities generally sickly?
4312. Because the air they breathe is not pure, but is (in the first place) defective in oxygen: and (in the second) impregnated with carbonic acid gas.
4313. Where does the carbonic acid of close rooms and cities come from?
4314. From the lungs of the inhabitants, the sewers, drains, and other like places, in which organic substances are undergoing decomposition.
4315. What becomes of the carbonic acid of crowded cities?