not merely the oily part of the chyle or of the food; but is a new substance, or a new combination of the principles or elements, which is made probably in the secretory organs of the adipose membrane: the form of oil being made use of by Nature in preference to any other for the nutritious substance of the body, from its being the least liable to putrefaction, and from its containing the greatest quantity of nourishment in the least bulk. This circumstance was clearly proved by my valuable and ingenious friend the late Dr. Stark, who, in a course of curious experiments, made by weighing himself after living for some time on different sorts of food, discovered that a less quantity of suet was sufficient to make up for the waste of his body, than of any other sort of ordinary food; and that, when compared with the lean part of meat, its nutritive power was, at least, as three to one.

"I may here add another circumstance that occurred to me when I first thought on this subject, which is, that since we believe the oil, or animal fat, is re-absorbed from the adipose membrane to serve for nourishment to the body; and as some of the patients (whose cases have been related above) could not take food, the re-absorption therefore of this oil might not be so much the cause, as the effects of the disorder under which they then laboured: or, in other words, that upon some defect in the digestive organs, the powers of nature drew from their magazines of oil in the adipose membrane, a supply of that fluid then perhaps necessary for the use of the body. In order to clear up this point, I thought it would be a satisfactory experiment, to compare the serum of the blood of animals at different periods after feeding them. For, if the re-absorption of the oil was merely to make up for the want of other food, or, if the serum was white merely from a greater quantity of oil being taken up in order to supply the wants of the body, then the serum ought to be whitest in the animal kept longest without food, or whose body was most in want. And as I had found that geese had very commonly this white serum, though their chyle was transparent, I chose to make the experiment on them. I therefore took two of them that were very hungry, and feeding both of them with oats, one I killed four hours after, when I knew a part of the oats were undigested; and upon examining the blood, I found the serum whitish, and full of small globules ; on its being suffered to stand a little time, the white part ascended to the surface like a cream. The other was killed forty-eight hours after eating, when its stomach was found empty, and the serum of its blood quite transparent, and without any cream rising to the surface, or any appearance of small globules, when examined with the microscope.

X 2

Now,

Now, this experiment seemed to me decisive, and to point out clearly, that the whiteness of the serum was not occasioned merely by the body being in want of food, and therefore, drawing the oil from its magazines; because here the animal most in want of food had its serum least white; but was occasioned by the fat's being re-absorbed faster than it was used (from its place being supplied by the fresh chyle) and thence was accumulated in the blood-vessels, so as to give whiteness to the serum. And from the same observation it likewise appears probable, that the great re-absorption, and the accumulation of the fat in the vessels of the plethoric patients above-mentioned, was the cause of their want of appetite, and of their other complaints, and not the effect of

them.

May not therefore a too great re-absorption of the fat, and its accumulation in the blood-vessels, be now admitted as the cause of one species of a plethora ?

And may it not likewise be useful in some complains of the stomach, to attend to the whiteness of the serum? For, although fat be a substance little liable to disease, yet it may perhaps be sometimes so vitiated or may so incommode nature, that she may be obliged to take it up from her magazines, and to use it, or throw it out of the body. Whilst this is doing a sickness of the stomach, and want of appetite, may be indications of fulness; and therefore, instead of wanting remedies to strengthen the stomach, may require bleeding, and other evacuations.

An analytical Essay on the Scammonies of Aleppo and Smyrna, with some Observations on the reddening of Litmus by Resins: by Messrs. BOUILLON-LAGRANGE and VOGEL.

[Nicholson's Journal.]

THE two sorts of scammony are obtained from the root of a plant, that grows in Syria. The finest and purest scammony is procured by making an incision in the root, and drying in the sun the juice that exudes. But frequently, in order to obtain a larger quantity, the people of Syria and Natolia express the juice, and not only from the root, but from the stalks and leaves also. Often too they adulterate it, by mixing with it the juice of some other milky and acrid plants, as that of the spurges; or increase its weight by a mixture of ashes and other foreign matters. To know that

the

the scammony contains none of these heterogeneous substances, the buyer should break the lumps, choose those that are shining interiorly, and reject those that appear too black, burnt, or containing sand.

Aleppo scammony is light, of an ashen grey, shining, transparent in its fracture. That of Smyrna is very compact, heavy, of a darker colour, and more difficult to powder.

Examination of Aleppo scammony.

When this scammony is pure, it melts entirely on a heated plate of iron, and emits fumes of a nauseating smell. Triturated with water it renders it milky. With boiling water it concretes into a lump: the water becomes yellow, and has a bitter taste; but it is neither alkaline, nor acid; which proves, that this substance is not adulterated with ashes, as some authors affirm.

Alcohol at 40° [sp. grav. 0.817] produces a slight precipitate in this aqueous solution; and the acetat of lead occasions a yellow flocculent precipitate soluble in nitric acid.

The alcoholic tincture of scammony has a brownish yellow colour. It reddens tincture of litmus; and leaves on evaporation a yellowish white and transparent resin.

This resin dissolves entirely in nitric acid, which it colours yellow. The addition of water renders this solution slightly turbid.

It is equally soluble in a solution of pure potash, even without heat, when its colour is yellow: but, if heat be employed, it is brown. Water, even in pretty large quantity, does not precipitate any of the resin. If the solution be saturated with muriatic acid, the resin does not separate. This triple compound of resin, acid, and potash, claims the notice of practitioners; perhaps we may thus discover a solvent for resins, that water would not render turbid.

The part of the scammony that was not soluble in alcohol assumed a grey colour when dry. Treated with boiling water it coloured it yellow, and alcohol occasioned a white floccu lent precipitate in it.

To determine the proportion of the constituent principles of Aleppo scammony, we took 100 parts of this substance, and exhausted them by alcohol. The solution was yellow. A grey substance remained, which, when dried, weighed 26. 'The alcoholic solution was evaporated to a sirupy consistence. Cold water precipitated from it a resin, which formed a homogeneous mass. The supernatant liquor was clear and colourless. Evaporated to dryness a brown matter was obtained, soluble both in water and in alcohol, and precipitable

by

by acetate of lead. This substance appeared to be what is called extract. When dried it weighed 2 parts.

The resinous mass, separated and dried, was yellow, and weighed 60.

The 26 parts insoluble in alcohol were then treated with boiling water. After evaporation a glutinous matter remained, weighing 3 parts, and having all the characters of gum. The remainder consisted of fibres of vegetables and a

little silex.

The distillation of Aleppo scammony exhibited nothing remarkable. Its products were a very acid brown liquor, and a light, blackish oil. The coal was black, shining, and compact. It contained the carbonates of potash and lime, alumine, silex, and a little iron.

Examination of Smyrna scammony.

The fusion of Smyrna scammony is less complete than that of Aleppo. Instead of concreting into a lump with boiling water, it becomes clotty; but the water poured off has si milar qualities.

An equal portion of this scammony, exhausted by boiling alcohol, afforded a tincture of a deeper colour, though con taining less resin. By evaporation a brownish, transparent resin was obtained, weighing 28 parts. The matter insoluble in alcohol weighed 66. This residuum, treated with boiling water, coloured it yellow. The solution had a faint sweetish taste; and alcohol produced in it a flocculent precipitate soluble in water. On evaporation it left a thick glutinous matter resembling mucilage, soluble with heat in weak nitric acid, and letting fall on cooling a white pulverulent substance, that had all the characters of mucous acid.

In this experiment water took up only 8 parts of the matter insoluble in alcohol. The remainder was subjected to the action of nitric acid assisted by heat, which dissolved it with effervescence. Ammonia added to this solution threw down a precipitate solution in potash. Potash and oxalate of ammonia too occasioned a precipitate. This residuum therefore, beside vegetable fibres and the substance insoluble in water and alcohol, which appeared to be oxigenized extract, was composed of alumine and carbonate of lime.

This substance, being incinerated, left a whitish powder, soluble in great part with effervescence in muriatic acid. This solution contained alumine, lime, and a little iron. The

portion not soluble in muriatic acid, being treated with potash, yeilded a siliceous precipitate on the addition of an acid. The water employed to precipitate the resin left after eva

poration

poration a brown matter, weighing five parts, of a bitter taste, attracting the moisture of the atmosphere, soluble in alcohol, and copiously precipitated from its aqueous solution by acetate of lead. This substance exhibited all the properties of extract.

From this analytical essay therefore it follows, that Aleppo scammony is composed of

Resin.

Gum

Extract

.

60

3

2

Vegetable fibres, earthy matter, &c. .35

Though the resins obtained from the two sorts of scammony have considerable analogy, yet, as that of Aleppo is yellow, transparent, and friable, while that of the Smyrna is darker coloured, and more difficult to powder, we thought it would not be useless to ascertain, whether there was any difference in their medicinal properties. In consequence several physicians undertook to make comparative trials on persons of nearly similar constitutions, but they have not yet observed any dif ference in their purgative effects.

From the preceding analysis we may conclude, that scammony is a true gum-resin mingled with a little extract. It is true it contains much less gum than the other gum-resins, yet enough to form a milky liquor with water.

The action of the alcoholic tincture of scammony on litmus led us naturally to examine, whether the property of reddening this blue colour was owing to an acid. None of our experiments having furnished a direct proof of this, we made a comparative trial of some resins, which we subjected to the following experiments.

1. Sandarach. The resin is converted into a grumous mass by boiling in water. The filtered liquor remains clear; and, when evaporated to a certain point, slightly reddens tincture of litmus; its taste is bitter; it does not alter infusion of violets; it is not precipitated by alcohol, or acetate

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