In the first place, acids in general modify the consistence of animal matters; they produce disorganization in proportion to their concentration; some diluted acids, for example, nitric acid at five degrees, may serve when it is necessary to study the nervous system, but then the bones lose their saline particles and are reduced to their organic frame; the muscles are discolored and faded, as well as the viscera; the nerves alone remain of a very remarkable mother-of-pearl whiteness. Arsenious acid preserves bodies very well, but a single subject would require a killogram! Although the medical journals having spoken of a process discovered by Dr. Tranchini, of Naples, the commission judged it expedient to invite M. Gannal to repeat this experiment; a subject was injected with a killogram of arsenious acid and ten quarts of water; this subject examined by your commission, presented all the characters of a good preservation; but, on one hand, this process has been for a long time known, and on the other hand, the employment of it presents so many dangers, that in case of its success your commission would feel themselves obliged to proscribe it; effectually, when twenty subjects were under dissection, there would be twenty killograms of this poisonous substance at the disposition of the public. Concentrated acetic acid preserves meats, but dries them. This same acid diluted retards putrefaction, but softens the bones, as well as the muscles, which are discolored by its action. 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.