ACQUIRED DISEASES FROM INORGANIC GASES AND VAPORS.
Br a gas is meant a substance which is ordinarily known to us in the gaseous form of matter, like the air we breathe. A gas is incondensible into a liquid or solid under the ordinary atmospheric pressure, at common temperatures.
By a vapor is meant a more readily condensible aeriform fluid which has taken that form from a liquid or solid, under the influence of heat, and is diffused in the air. It is usual to speak of a vapor as being derived from the volatilization of some volatil izable body like water-vapor, steam,---from heated water.
Sometimes gases or vapors, given off from various substances, are called fumes. The vapors given off from heated resin, from phosphorus which is being oxidized, from mineral acids, such as the nitric or hydrochloric, are commonly called fumes. I prefer to speak of them as gases or vapors.
Gases and vapors when inhaled pass, like the air, into the windpipe and lungs. Diffused with the air, they may reach the blood which has been sent from the right side of the heart to the lungs, and absorbed by it may enter the blood-stream and condense in it. They have, therefore, a general as well as a local action.