Hydrogen sometimes also unites with sulphur, and the combination is called sulphuretted hydrogen, a gas readily discovered by its offensive odour,—which it imparts to many very useful mineral waters.
These gases are discovered, not only in an atmosphere exposed to decomposing dead animal materials, but are also found in that atmosphere containing numbers of men in health, closely crowded together, and persons suffering putrid diseases, where no attention is paid to cleanliness and the removal of impurities.
A body affected with putrid disease is more liable to decomposition than one in health; and the secretions and excretions are more prone to putrefaction, and the emission of effluvia or gases.
Some facts are known, which shew that bodies, in some forms of low or malignant disease, both before and after death, possess a virulence, never found in bodies in health, or affected with disease of a non-malignant character. The worst consequences have followed wounds in the dissection of bodies recently dead of typhus fever; the introduction, under the skin, of the fluid contained in the petechiæ or black spots common in that disease, and even the washing of bandages and clothes employed in cases of mortification and the like.
In such diseases, the body becomes a very centre of contamination and virulence; its fluids become acrid and poisonous; and on the surface of the body, fluids are elaborated, which are productive of the most malignant and pestiferous effects. Whether these fluids, those virulent secretions, are ever diffused in the air, and impart to it their deadly properties, is a point of much interest, but one which cannot be entertained here.
CHAPTER VI.
AIR VITIATED BY ADMIXTURE WITH EFFLUVIA ARISING FROM THE DECOMPOSITION OF VEGETABLE MATTER ON THE SURFACE OF THE EARTH.
It is not only from such sources as those already treated of, that effluvia or gases arise, to contaminate the atmosphere, and to spread disease among men and beasts. Effluvia likewise spring from the putrefaction of vegetables; and, in many instances, from circumstances favourable to their development and action, they so vitiate the atmosphere, that its respiration induces some of the most virulent diseases, and, where the effects are not so serious, a state of slow sickness and great suffering is often the lot of the sufferer, during the whole course of his miserable existence. The situations of these effluvia will shortly be pointed out, along with the respective diseases incident to them.
But let us for a moment consider the changes on which these effluvia depend. Putrefaction of vegetable matter is one of the many wise provisions which the Almighty has instituted for the accomplishment of his comprehensive plan of the creation.
The surface of the earth is covered with vegetation, to supply man with food, and likewise to support the various animals placed below him in the scale of creation, so necessary to his comfort and existence. They are consumed, and, by means of digestion, become component parts of animals; and when these, in their turn, die, they go down to the earth, whence they originally sprung.
Mixed there, with other matters composing the soil, the carcasses of animals afford nourishment to vegetation again, and once more they are found as the component principles of vegetable forms. Thus the animal is constantly supplying food to the vegetable world, which, in its turn, supplies food to the other again.