Cobalt, 1 ℥. Alum, 2 ℥. To be powdered and mixed. Before employing this powder, give a layer of essence of pine, (turpentine,) in order that it may adhere better to the interior of the skin. If the latter be very greasy, add an ounce and a half of lime decomposed in the air and sifted. Among the preservatives which this naturalist has investigated, we find a very simple one, which he says, is very effectual for mammifera: the following is its composition: Cobalt in very fine powder, 4 ℥. Alum, 4 ℥. The same naturalist recommends another composition as very good, and which I think would be worth making a trial of for large animals, which would be very expensive done with arsenical soap. Very fat bitumen is to be melted, in a strong solution of soap-water, until the whole forms a sort of clear broth; the interior of the skin is to be endued with this mixture, which costs very little. _Preservatives in Liquors._ Liquors are employed in baths, in lotion, in friction, in injection, and finally, in permanent baths, in which certain objects are always to remain; we shall now treat of these four methods of preservation. _Of the Bath._ In many animals, and particularly in the mammifera, the skin has such a thickness, such a degree of intensity, that the arsenical soap can not penetrate it sufficiently in order to preserve it perfectly; it is then that the bath becomes an indispensable operation. In penetrating the skin which is left to macerate a longer or shorter time, the preservative molecules with which it is saturated enters all its pores, and preserves it for ever from the attacks of insects. The following is the composition of the bath employed by the naturalists--preparors of Paris. ℞. Common water, 5 ℔. {pints} Alum, 1 ℔. Sea-salt, 1/2 ℔. This mixture must be boiled until it is all entirely dissolved, and when the liquor has cooled, plunge the skins into it; those of the size of a hare, or thereabouts, need not remain longer than twenty-four hours; those of the larger animals must macerate a longer or shorter time, according to their thickness; from eight to fifteen days would not be too long for a buffalo or a zebra. At the museum of Natural History of Paris, they very rarely make use of this composition; they are satisfied to macerate the skins in spirits of wine, which they keep in hogsheads for that purpose. Without attempting to criticise this method, which may have its advantages, we think that they might, perhaps, in this particular, follow the English naturalists, and add, like them, a small quantity of corrosive sublimate dissolved in spirits of wine.