In an English Medical Journal, for the year 1818, we find, that it is proposed to replace alcohol by _rock-salt_, for the preservation of anatomical and natural history subjects, which is known to be nothing more than muriate of soda, purer than that of commerce; this proposition is inadmissible. The chlorides of the oxides of calcium of sodium, of potassium, have been recommended for some pieces of pathological anatomy; but they are not applicable for the preservation of thick objects, and much less entire subjects. Wine to which has been added a nitrous solution of mercury, has been employed by some navigators, for the preservation of small zoological collections; its use cannot be employed extensively. Acids, more or less diluted, alter the tissues, and attack the dissecting instruments. Aqueous or alcoholic solutions of the salts of mercury, arsenical solutions, &c., are dangerous, by their emanations, for the anatomist who constantly handles the objects impregnated with these metallic salts; and further they harden the tissues, contract them, destroy their colours, and attack anatomical instruments. We may repeat of the pyroligneous and acetic acids, what we have already advanced of the other acids. Nevertheless, it was proposed about fifteen years ago, to use the pyroligneous acid, as excelling in its properties for preserving animals, and anatomical subjects. All acids, not excepting vinegar, attack the colour of organic tissues, corrode them, and deprive the bones of their earthy salts, rendering them flexible and transparent, and cover the soft parts with a layer of gluey matter which conceals the fibres and the structure of the parts. It is known that alum and nitre are employed separately in aqueous solution, to preserve anatomical preparations, during the time of their fabrication. It is known that anatomists employ nitre, or simply saltpetre of commerce, not only to preserve the fleshy tissues,[Q] but to give a lively red colour to the flesh. [Q] Nitre possesses no preservative properties.--_Tr._ We have thus, gentlemen, in a cursory manner, exposed the ordinary methods proposed or employed for the preservation of animal matters. In order to respond to the Academy upon the merits of the discovery of M. Gannal, we will say that his process consists of an aqueous solution of three salts, already employed separately in the anatomical laboratory, _nitre_, _common salt_, _and alum_. We have caused to be repeated under our inspection the experiments of M. Gannal. In the course of last March, two bodies were placed in a bathing tub six feet six inches long, sixteen inches wide, and twenty inches high. A liquor was poured upon these bodies, composed of acid sulphate of alumine, and of potash, of the chloride of sodium of each two parts, and one part of nitrate of potash.