The solution of this substance in potash is slightly brown, its smell is not strong, the acids precipitate it in the form of white flocks, and disengage a very fetid odor. When acetate of lead is dropped into the solution, a dark brown precipitate falls, showing obviously the presence of sulphur.

Five grammes (77.2 grains troy) of this matter cautiously distilled, furnished carbonate of ammonia in crystals, and a red oil having a smell similar to that of albumen decomposed in the same There remained in the retort 1 gramme (15.4 grains troy) of charcoal, which required 5 grammes of nitre to be entirely burnt.

manner.

The solution of salt obtained from it left 5 centigrammes (0.77 of a grain troy) of earthy residue, which was phosphate of lime. The liquid being supersaturated by nitric acid, and subjected to ebullition, let fall no precipitate; but it yielded a copious one when mixed with lime-water. This shows that the phoshate of magnesia had been decomposed by the potash, and perhaps even a portion of the phosphate of lime.

This matter, heated alone in a crucible, decrepitates, swells, and melts like albumen. Its charcoal, though calcined for a long time, does not become acid like that of the fatty matter; which shows that it contains no phosphorus. This charcoal, being washed with muriatic acid, furnished a small quantity of phosphate of lime and phosphate of magnesia.

When thrown into melted nitre it burns rapidly, and with flame; and we find, in the alkali resulting from that operation, very sensible traces of sulphuric acid, though the saltpetre employed contained none of it. This proves that the matter of the brain which is insoluble in alcohol contains sulphur; and confirms what was indicated by the acetate of lead dropped into the alkaline solution of this substance.

The properties which the portion of the brain insoluble in alcohol has presented, leave no doubt that it is perfectly identical with albumen. The knowledge of this circumstance explains very well the coagulation of the brain mixed with water by heat, acids, metallic salts, &c. This was the opinion which Fourcroy had formed of this substance in his memoir on the subject published in the Annales de Chimie.

SECT. IX.-General Result.

The mass of the brain, then, is composed of the following sub

stances:

1. Two fatty matters, which are probably identical.

2. Albumen.

3. Osmazome.

4. Different salts; and among others, phosphates of potash, lime, and magnesia; and a little common salt.

5. Phosphorus.

6. Sulphur.

I conceive, as far as it is possible to draw conclusions from ex

periments

periments so delicate, that these substances exist in the brain in the

SECT. X.-Putrefaction of the cerebral matter.

A portion of brain being diluted with a certain quantity of water, and abandoned to itself during a month, presented the following phenomena. At first it separated into three parts. That portion which occupied the surface was a part of the matter of the brain elevated by air bubbles attached to it. The portion in the middle was a yellow colored liquid, which, after an interval of some days, assumed a fine red color, which it retained for more than twenty days. After that period, this color by degrees faded, and was succeeded by a yellow color, more intense than that which the liquid had formerly possessed. The third portion, occupying the bottom of the vessel, was another part of the matter of the brain. During the month that it was allowed to remain, it emitted no gaseous matter,

The vessel containing this mixture being left open, there issued out of it an invisible vapor, having a disagreeable smell, somewhat similar to that of putrid cheese. Some persons compared it to the "odor of the intestines when beginning to decompose.

A paper dipped in the solution of acetate of lead being exposed to this vapor, assumed immediately a blackish brown color.

The liquid in which the brain had thus putrified was sensibly alkaline; at least it restored the color of litmus paper reddened by acids, and formed white vapors when oxymuriatic acid was brought into its neighbourhood.

The liquid separated by filtration from the matter of the brain had an amber color. Acids rendered it muddy, throwing down white flocks. The odor which it exhaled in these circumstances was more fetid and disagreeable than before. Oxymuriatic acid rendered it muddy, likewise; but at the same time entirely destroyed its odor.

After being filtered, the liquor was subjected to distillation. As soon as it was heated nearly to the boiling temperature, yellow flocks separated in abundance, as happens when a diluted solution of albumen is treated in the same manner.

The product of the distillation was without color. Its odor was perfectly similar to that of the liquid before distillation. It precipitated acetate of lead white, and restored the color of litmus redNO. 173.

K

dened

dened by an acid. Oxymuriatic acid destroyed its odor, and made it assume a yellow color.

When the liquor remaining in the retort was reduced to about a fifth part, it was filtered. Its color was yellow, and its edor similar to that of old cheese. It had become acid, for it reddened the color of litmus paper. Infusion of nutgalls, lime-water, and alcohol, formed flocky precipitates in it. Ammonia also occasioned a granular and semitransparent precipitate, which resembled ammoDiaco-phosphate of magnesia. Concentrated sulphuric acid being mixed with this liquid developed a strong smell of vinegar.

The solid matter of the brain which had undergone fermentation, being washed with water, and submitted to the action of alcohol, communicated to it a bluish green color, as if the brain had undergone no alteration. This alcohol, on cooling, deposited a white matter, partly in flocks, partly in crystals. There remained a greyish substance, which the alcohol had not dissolved, and which resembled albumen.

From these experiments we may conclude,

1. That the fatty portion of the brain had undergone no sensible change during the putrefaction of this organ. It preserved the property when dissolved in alcohol to give it a green color, and to precipitate, on cooling, in a crystalline form, and retaining all its properties.

2. That a part only of the albumen was destroyed by the fermentation; that from this decomposition a small quantity of ammonia resulted which dissolved another portion of the albumen, and some acetic acid rendered sensible by the addition of sulphuric acid.

3. That the osmazome was not decomposed, at least completely, since its presence was still recognised in the concentrated liquid.

We conceive that the albumen of the brain putrifies much more speedily, and undergoes a more complete alteration, when it is in contact with the air than when it is confined in a close vessel.

I do not know what the substance is which assumes a red color during the putrefaction of the brain. I thought at first that it was the substance which gives a green color to alcohol; but I gave up that opinion when I saw that the cerebral matter still communicated the same color to alcohol after its putrefaction.

The cerebellum of mas, and the brain of herbivorous animals, being examined in the same manner, and with the same precautions, yielded the same results. I propose to continue these researches on the brain of other classes of animals.

SECT. XI.--Of the medulla elongata, and spinal marrow.

The medulla elongata and spinal marrow are of the same nature as the brain; but they contain much more fatty matter, and less albumen, osmazome, and water. Hence the reason why the spinal marrow has greater consistence than the brain.

The spinal marrow communicates to alcohol, when boiled in it, a blue color, as the brain does. It contains, likewise, superphosphate

of

of potash. The portion insoluble in alcohol is of the same nature as that of the brain; that is to say, albumen. The fatty matter contains phosphorus, like that of the brain,

Of the nerves.

The nerves are likewise of the same nature as the brain; but they contain much less fatty matter, and green coloring matter, and much more albumen. They contain, besides, common fat, which separates from them when treated with boiling alcohol, and deposites itself at the bottom of that liquid.

The nerves, deprived as much as possible of their fatty matter by means of alcohol, become semitransparent. Treated for a long time in that state with boiling water, they do not dissolve; but become white, opake, and swell up, obviously in consequence of absorbing moisture. The water in which they were boiled holds in solution a small quantity of matter; for the infusion of nutgalls forms a precipitate in it, and the solution properly evaporated yields a little jelly, derived, probably, from the cellular texture which binds the nervous fibres together.

After having been treated with alcohol and with water, the nerve dissolves almost completely in caustic potash. Only a few flocks remain, not amounting to the hundredth part of the mass employed. No ammonia is produced during the solution.

The solution of nerve in alkali is precipitated by acids, and the precipitate, as well as the liquid from which it fell, assumes a purple color.

Nerve preserved in water undergoes little alteration. The water, however, after a few days, assumes the odor of semen very sensibly. Nerve put into oxymuriatic acid contracts its dimensions.

As it is chiefly the envelope of the nerves which undergoes this change, the nervous substance issues from its case, and each of the fibres which compose it separates from those in its neighbourhood; so that the nerve looks like a hair-pencil with its extremities diverging. In this situation the substance of the nerve assumes more consistence and whiteness, owing to the condensation and opacity which it requires. From this experiment, it would seem that oxymuriatic acid would furnish a good instrument for facilitating the study of the nerves and their envelope.

Is it possible, from the experiments to which the brain has been subjected, to determine the state in which each of the elements composing this organ exists in it? Is not the albumen united to a portion of phosphoric acid, and is not its consistence and opacity owing to this combination? Without affirming any thing on this head, I will say, that this substance appears to have acquired its state of semicoagulation from an acid; just as happens to the eurdy part of, sour milk; and that this coagulation is produced entirely by a fermentation, which commences, like that of milk, by being acid.

I next proposed to myself this question: Is the fatty matter in combination with the albumen and the osmazome? This scems to

be the case, at least with regard to the fatty matter and albumen ; for when the matter of brain is triturated with water, and converted into a species of emulsion, if it be left at rest the albumen and fatty matter separate together, and the osmazome remains in solution in the liquid, together with a small portion of the albumen. At the same time, I acknowledge that it is possible that these two substances are only in the state of mixture, and that the albumen here performs the same office to the fatty matter that mucilage* does to the oils of emulsive seeds.—Annales de Chimie, vol. lxxxi. p. 82.

CRITICAL ANALYSIS

OF RECENT PUBLICATIONS

IN THE

DIFFERENT BRANCHES OF PHYSIC, SURGERY, AND MEDICAL PHILOSOPHY.

Edinburgh Medical and Surgical Journal, No. XXXIII. I. Case of Congenital Cataract; with some Observations on the Means of Artificially Dilating the Pupil in the Operations of Extracting and Depressing the Cataract. By JOHN HENRY WISHART, Surgeon.

1

HIS case of congenital cataract differs so little from many others which have lately been laid before the public, that it will be useless to repeat it: serving, however, as the motive for giving a short historical account of the employment of certain narcotic vegetables for dilating the pupil, it is entitled to our consideration.

The accidental acquirement of the fact of the Atropa Belladonna, when applied to or near the eye, causing a temporary dilatation of the pupil, interesting and valuable as it is, remained long without any useful practical appropriation. The account given by Ray, (Hist. Plant. L. xiii. c. 23, p. 680) and copied by Van Swieten into his Commentaries on the Aphorisms of Boerhaave, (Aphor. 1060) and even the observations of Galen, (Method. Medend, lib. iii. cap. 11, tom. x. p. 58. Charter) that opium, mandrake, and henbane, produce the same effect, excited no attention beyond the simple fact; nor was this property, diffused, probably, among a large family of plants, turned to any account, until a gentleman who was preparing the extract of the Belladonna

* I call mucilage, with all the chemists, the substance which holds the oil in suspension in the emulsion of almonds, though it be of a very different nature from gum.

for