2. In 1835, Dr. Beniquet having to pursue some investigations on the brain, he made use of my liquor in order to preserve entire heads, for which he had occasion. After his experiments were finished, he presented to me a head which remained, and which I preserve in my cabinet. It is impossible to detect the slightest trace of change in it.
3. I have preserved unaltered for three months, the head of a Bar, (a species of Silurus,) weighing several pounds; this head has served for dissection.
4. I have preserved leeches and other worms for several years, without perceiving that they had lost any of the characters necessary for the naturalist to know.
5. The same observation applies to the different organs of birds and mammalia: the heads of pheasants plunged, feathers and all, into the preservative liquor, after fifteen days of maceration, present the red colour around the eye of as lively a shade as at the moment of immersion.
I might multiply these examples, and produce several hundred trials equally conclusive, made during the course of my experiments; but as it could not result in any advantage to the reader, I forbear. Besides, the use that Captain Durville has made of my liquor during his scientific voyage, and the thousand proofs to which it is every day subjected on the part of men, whom the study of natural history induces to have recourse to it, will be the most faithful and sure confirmation.
In fine, I shall always be most happy to receive the observations, remarks, and criticisms of those, who, with an interest for science, may have occasion to point out to me any circumstances calculated to modify the applications. Many, without doubt, may have escaped me, and as I desire, above all things, to bring my processes to the highest degree of perfection, I shall be thankful for any aid that may contribute to this end. The following is the composition of the liquids[S] which I employ for preserving the different pieces of normal anatomy, pathological anatomy, and natural history.
1. A solution of the simple sulphate of alumine, at six degrees; that is to say, the solution of a killogram of this salt in six quarts of water.
2. A solution of simple sulphate with water saturated with arsenious acid:—five hundred scruples of arsenic to forty quarts of water;—six quarts of this solution to one killogram of the simple sulphate.
3. Of the acetate of alumine at five degrees, saturated with arsenious acid.
Usage.—For fifteen days I cause the pieces to disgorge in the first liquid; at the end of this period they are withdrawn and placed in the bath of a second liquid, where they may remain for from three to five months; finally, they are withdrawn and placed in a third liquid. It is thus that I have preserved preparations for three or four years, which the public is welcome to come and see.