mains flaccid, and, when boiled, dissolves away to mere membrane, and has a weak, watery, and insipid taste; the muscular fibres are pale and wasted, but the fat seemingly remains. It, however, appears dry, dead white, and brittle, or shining with water, and in its nature it is completely altered, for it does not melt or inflame like an unctuous substance, but when thrown on the fire, crackles and blackens to a cinder. Very little blood is found in the animal, and it is pale and thin, resembling water tinged with blood, rather than blood. The bones are remarkably brittle.” P. 126.28.

The causes which contribute to the production or prevalence of the rot, may be considered as depending upon the soil, on the weather, and on the animal itself.

"Whatever injures the constitution, or tends to debilitate sheep, also renders them more liable to be affected with the rot. Nothing contributes more than a course of changeable weather from one extreme to another, to waste sheep, and nothing is more difficult to guard against, which has given rise to the proverb,

Mony frost, mony a thow,

Soon makes mony a rotten ewe.

"Overheating sheep in autumn by severe dogging, or rash and inconsiderate management, has also the worst effects in breaking their spirits, and wounding their constitution. Ever afterwards, they feed only on soft tathy meat, which always insures rot in the spring. Ewes, and especially gimmers, which have been debilitated by being milked, or sucked too long, commonly suffer. The rot may be also considered as an hereditary disease, at least the lambs of tainted ewes are never sound."

Sheep that have plenty of food and good shelter, are said never to be affected with the rot. This, however, is not always true; the appearance of the disorder seems to be owing to any sudden change of food; and one of the authors asserts, that it is always occasioned by a too quick transition from fatness to leanness.

Cure." As soon as there is any appearance of the rot, such food as they delight in should be offered to them, and their appetite excited by a little gentle exercise. As long as their bellies are light, a bite of broom, heather, or sea-marsh, twice a-day, will, in general, recruit them. Salt is a known antidote in this disease. Sheep are also na. turally fond of salt, when they have free access to it. They have been known to run to salt in wooden backets and to lick the salt bags hung up in their folds; to eat salted hay, and to drink out of cisterns having salt in solution among the water. On a small scale, it may even be given in water by the hand, and poured down their throats. Of all medicines, it is the safest and most effectual against this distemper.

"With respect to the cure of it by medicines, little can be said with certainty. The leaves of elecampane, coltsfoot, honey, plantain,

foxglove,

foxglove, &c. have all been recommended, but undeservedly, except the foxglove, which seemed to Mr Stevenson to arrest materially the progress of the disease, in those cases in which it was tried. A handful of the leaves was boiled in a Scotch pint of water, until it was reduced to three mutchins, and of this decoction, two tea-spoonfuls were given three times a-day, with a little molasses and water.

The following receipt has been recommended as very efficacious: Steep four pounds of antimony in two gallons of ale, for a week, and give the sheep a cupful of it night and morning.

Of these dreadful effects of unwholesome food and bad air, some perhaps are imaginary, and some may have another cause. That the disease commonly called rot, and all the maladies which proceed from debility, poor food, and improper management, are less frequent now than in any former time, seems undoubtedly true; but organic affections of the lungs or the liver will not be entirely expelled in this climate, by draining all the wet lands in the united kingdoms. The annual losses of sheep are very great; it therefore becomes an important consideration to diminish them, and draining appears to be the best preventative. One of the authors, whose essay is analysed in this treatise, is a Mr Stevenson, who combines the twofold character of surgeon and farmer; his observations are more scientific than the rest, and he relates some cases to shew the efficacy of certain remedies. He has made several classifications, which are given in the appendix, and the following may be quoted as likely to prove useful to persons in the country, who choose to engage in any inquiries relative to comparative pathology.

No. VII.

Classification according to the nature of the disease. By Mr Stevenson. Diseases attended with Fever'; including,

VIII.

Dissertatio Chemico-Medica Inauguralis, de Acid Urico, et Morbis à Nimia ejus Secretionie Ortis. Auct. GULIELMO HENRY. Edinburgh, Sept. 1807.

THE subject of this dissertation is only a branch of a much more extensive one, in which the author states that he is engaged, viz an inquiry into the composition and remedies of urinary stone, and gravel in general. These concretions, it is now well ascertained, are composed, in different cases, of very different ingredients. A large proportion of them, however, consist of the uric acid, a substance which is always present in the urine, even in its most healthy condition; and the properties of which, though investigated by several distinguished chemists, Dr Henry found, had not, in some respects, been ascertained with sufficient precision. The experiments detailed in his inaugural dissertation, were therefore instituted, previously to the examination of such calculous concretions as are composed wholly or chiefly of the uric acid.

The First Section gives an historical view of discoveries respecting the uric acid, from the time of Van Helmont to the present day.

The Second Section affords a detailed account of the properties of the uric acid, both as established by the author's own experiments, and by those of other chemists. They are to be understood of the purified acid, obtained by the solution of calculus in pure potash, precipitation by muriatic acid, and copious ablution with water.

In this state, the uric acid is a perfectly white powder, entirely destitute of taste and smell. The colour, and other sensible properties, which it usually exhibits, arise entirely from foreign admixtures. It is not dissolved by less than 1150 times its weight of boiling water, or 1720 parts of water at 60° Fahrenheit. The solution, on cooling, deposits a number of small crystals, and gives a red tinge to infusion of litmus; which change is still more distinctly effected, by heating the blue infusion with the powdered acid. No effervescence is produced by the admixture of this solution with one of an alkaline carbonate.

The well known property of affording a bright red substance by evaporation to dryness with nitric acid, Dr H. finds to belong

to

to the uric acid, when attentively purified; and not to depend, as Fourcroy asserts, on the admixture of urea.

After the most attentive experiments, Dr H. has proved, that the alkaline carbonates, or sub-carbonates, do not exert the smallest solvent power over the uric acid. This fact is important in a medical view. The acid, however, is rapidly dissolved by solutions of pure alkalies, especially the fixed ones; and though less quickly, by lime water and a solution of soap, from which last, with the aid of heat, it detaches the oil. It is dissolved, also, by sulphurets and hydrosulphurets.

the

The uric acid is capable of uniting with alkalies, &c. in two ways; 1st, To the point of saturation, forming urates, properly so called. The properties of these compounds, all of which are very difficultly soluble in water, Dr H. has investigated with great minuteness; but we refer, for the details, to his thesis, because, though interesting to the chemist, they have no connection with medical practice. The sub-urates, or urates with an excess of alkali, are readily soluble; and these must necessarily be compounds which are formed, if in any case we successfully attempt the solution of calculous concretions within the body. The urates and sub-urates are decomposed on the addition of acids. If, however, a weak acid (as the carbonic or prussic), or only a small quantity of a stronger acid, be added to a sub-urate, the precipitate is not uric acid, but a saturated urate. To this circumstance Dr H. thinks it of importance to attend, in preparing the purified acid for the purpose of experiment; and he is of opinion that the errors of some chemists have arisen from their operating on a saturated urate, and not on uric acid; in consequence of which, they have been led, without sufficient grounds, to deny the acid nature of this substance. In precipitating uric acid from an alkaline solution, the acid employed should be added suddenly, and in considerable quantity.

The decomposition of the uric acid, by various agents, is next fully described. Our limits, however, only allow us to state, that the sublimate, obtained by distilling the acid per se, Dr H. finds to consist of ammonia united with a peculiar, and hitherto undescribed acid, differing essentially from the uric, benzoic, and succinic acids; and the properties of which he reserves for further examination.

Section Third. Of the generation of the uric acid within the body. On this obscure subject, the author laments there is such a paucity of facts, that, in the present state of physiological science, it is impossible to form a rational theory respecting it. From the experiments of Dr Wilson, however, there appears to be a connection between the presence of acid in the prime viæ,

whether

whether generated there or taken as a part of diet, and the increased appearance of uric acid in the urine. Suppressed perspiration, also, augments the secretion of this acid. With respect to the influence of impure or hard water, in generating stone and gravel, Dr H. apprehends that it is an unfounded prejudice; and states, that so far as his experience extends, hard waters are rather unfavourable to the production of calculus.

Section Fourth.-On the cure of the diseases which arise from an increased secretion of uric acid.

The only diseases which can, with certainty, be ascribed to an increased production of uric acid, are certain varieties of urinary stone and gravel. Gout has also been said to have a connection with the same cause; but this is rather matter of speculation than of experience.

The indications in the cure of diseases depending on this cause are reduced by Dr H. to two: 1st, By giving tone to the stomach, and to the system in general, to prevent the further morbid production of uric acid; and, 2dly, to remove any portion which may already be accumulated.

For the solution of uric concretions, when actually formed, he is of opinion, that soap, lime-water, and, above all, the pure fixed alkalies, all of which have long been used with this view, are the only means deserving our confidence. But though the carbonated alkalies, under the various forms of soda pilis, soda water, &c. cannot possibly, as appears from the author's experiments, possess any solvent power over uric concretions, he does not deny their utility, which seems, indeed, sufficiently established as a matter of experience. He apprehends that the mild alkalies act by neutralizing any acid in the alimentary canal, which may have been formed by depraved digestion, and by preventing the further morbid generation of uric acid. When the urine is thus deprived of its depositing power, he thinks it may, itself, exert the property of a solvent, in at least the same degree as water; and, by its continued, though slow operation, may even remove small concretions. Large and hard masses of uric acid, formed in the urinary passages, he is of opinion, no solvent can remove, whether taken by the mouth, or injected into the bladder; and he limits the use of pure alkalies to the early stages of the disease, and to that variety of it, in which the concretion takes the form of stone or gravel. His rules for the regulation of diet and regimen, we are prevented, by our limits, from inserting.

We readily concur in giving publicity to Dr Henry's request, for the communication of specimens of urinary concretions, in order that he may be enabled fully to prosecute an inquiry of considerable importance to the art of medicine. The calculi may