Now, these salts[48] when placed in contact with animal and vegetable substances, perform the same function as in the lungs: they take a part in the combustion going on, and, as in the living body, are converted into carbonates. Left to themselves for a time, from their aqueous solution, the acids composing them finally completely disappear.
Mineral acids and nonvolatile vegetable acids, as well as mineral salts with an alkaline base, have the property, when sufficiently concentrated, to arrest the whole process of this slow combustion;[49] common salt, as is well-known, arrests putrefaction: so does alcohol.
The chemical action of certain other mineral salts is different, such as the salts of the peroxide of iron, of lead, bismuth, copper, and mercury. These are inorganic poisons. They combine with the tissues of the organs, and so destroy life. The mode of action of the poisons of prussic acid, strychnine, morphine, &c., is as yet unknown.
“But there exists a class of substances no less fatal than the preceding, originating in certain decompositions. In a preceding Chapter (III.) we have inquired into the origin of these poisons, and shown them to originate in fermentation and putrefaction. Let us apply the chemical principles regulating these processes to organic matters, to the products of the animal economy; all the elements of these matters are derived from the blood, the most complex of all existing substances. In decomposing, a poison is occasionally produced speedily mortal when it comes in contact with the blood of the living animal. The venomous principle produced by decomposing animal bodies is not always the same: that originating in certain German sausages is quite peculiar; the person who partakes of this fatal dish dies mummified; he does not rot or fall to pieces like those who perish from wounds received in dissecting-rooms; on the contrary, he dries up and withers, but does not putrify.[50] Liebig, the discoverer of this poison and its effects on man, states that the venom is destroyed by boiling-water and alcohol, but that these do not absorb it.
[50] All constitutions are not equally liable to be affected by morbid poisons. This has been proved as regards dissecting-room wounds; and as regards typhus, cholera, plague, ague, &c., the matter admits of no doubt.