The alkaline salts only preserve meats when they are used dry, or in a very concentrated solution; it is necessary in this case that the salts preserve an affinity for the water of composition, so that it may be said that these salts preserve meats because they dry them; thus, on this principle, salts more soluble in warm, than in cold water, may, injected as a warm concentrated solution, be considered as a means of preservation; this applies particularly to the nitrate of potash.
Creosote, a newly discovered vegetable substance has been recommended as a preservative of flesh; this fact demanded verification: a corpse which had been injected on the 18th of October, with one hundred scruples of creosote and seven quarts of water, was decomposed on the 30th of the same month.[R] But, in order to respond to the objection which was made, that the body should have been immersed in a bath saturated with creosote, it is sufficient to say that this bath would have cost forty dollars; besides the necessity of combatting the odour of the creosote, which may prove an obstacle to anatomical labours.
A solution of alum at eight degrees has succeeded better; but the flesh becomes hardened, faded, and friable.
The mixture of alum, (acid sulphate of alumine, and potash,) two parts, the chloride of sodium two parts, and of nitrate of potash one part, dissolved in water, employed as a bath, has afforded the first good results.
The acid phosphate of lime is the first substance which has been employed in injection for subjects; this salt did not oppose the movement of putrefaction.
The kidnies, injected with this salt, and immersed in the milk of lime, became hardened at the surface and putrefied in the interior.
After this first part of the experiments of M. Gannal, it results that the aluminous salts are those alone which succeed well in preserving animal matters, and which may be used advantageously.
Alum, employed alone, preserves well, but for a short time; this salt, slightly soluble in cold water, (fifteen degrees,) will not suffice as an injection for the preservation of a body; it is indispensable to immerse the body in a bath of the same salt.
The mixture of alum, salt, and nitre, as indicated in the provisionary report, has not the same inconvenience; a subject injected with this liquid, at ten or twelve degrees of density, may be preserved for more than a month; but it is indispensable to immerse it, at least from time to time, when it is desirable to prolong its preservation; that is to say, for the entire winter; but at a temperature above fifteen degrees, it is necessary to inject the liquid at a density of twenty-five or thirty degrees, and, in order to obtain it, it requires to be heated at least to forty degrees.
Several bodies injected with this liquid at ten degrees, on the 2d of December, 1834, were well preserved until the end of April; other subjects, injected on the 7th of August, but with the liquid at twenty-five degrees of density, and at ten degrees of the thermometer, were still, on the 10th of December, in good condition, whilst those that were injected with a liquor of inferior density, did not resist a temperature of twenty or twenty-five degrees, although they were immersed in a bath denoting fifteen degrees. The bath of salted liquid has, independently of the inconvenience of expense for the necessary salts and the embarrassment of the tubes, which require frequent renewal, the objection of hardening the skin, considerably.