from the exhaustion of oxygen, but also from the circumstance that the confined atmosphere may become azotized or surcharged with carbon to the limit of its absorbing powers, just as water, after being saturated with certain percents of salt or sugar, refuses to dissolve any further additions. The act of reinspiring air, which has already been subjected to the process of pulmonary digestion, is thus precisely analogous to the act of a famished animal devouring its own feces, and if performed habitually cannot fail to be attended with equally ruinous consequences. Corruption of the alimentary ducts would surely ensue in the latter (supposed) case, putrefaction of the respiratory organs does follow in the other. Working-men employed in localities whose azotized atmosphere is loaded besides with particles of flying cotton-fibre, metallic dust, or fatty vapors, inspire substances which are just as indigestible to their lungs as mercury and alcohol are to their stomachs, and like these cause a rapid deterioration of the tissues in proximity to which they are deposited.
The only wonder, then, is how Nature can resist outrages of this kind for any length of time; and it is a curious reflection to think what amounts of hardship of the primitive sort, such as hunger, fatigue, cold, heat, deprivation of sleep, etc., a healthy savage might accustom himself to, if he tried as hard as the poor children of civilization try to wean themselves from their hunger after life-air!
Can necessity be—we will not say an excuse, but—an explanation of such systematic self-ruin? We must utterly refuse to believe it. Wherever men barter life for bread, there is a violent presumption that they do not know what they are doing; for against recognized health-destroyers even the poorest of the poor will rebel with a prompitude that vindicates the dignity of human nature under the most abject conditions of bondage. Let a railroad contractor be caught in the trick of adulterating his flour with chalk or his sugar with alum, and see how quickly his navvies will leave him; or observe how firmly reckless Jack Tar insists on his anti-scorbutic raspberry-vinegar! Miners have left a colliery en masse, because the owner shirked his duty of providing safety-lamps; and the very negro slaves of a South Carolina plantation attempted the life of their master, who stinted their allowance of quinine brandy which his father had issued them to counteract the miasmatic tendencies of the rice-swamp.
Neither is it possible to suppose that want of hygienic education can be the origin of such ignorance; for Nature does not wait for the scientist to inform her children on questions of such importance. All normal things are good, all evil is abnormal; vice is a consequence of ignorance only in so far as it is a result of perverse education, and the troglodyte-habit is the direct offspring of mediæval monachism. Until after the fourth century of the Christian era, habitual in-door life between closed walls was known only as the worst form of punishment. Though the Greeks and Romans were familiar with the manu-
