On the fubject of Vegetation, the author is a little incon fiftent. Let us take his own words, where he endeavours to reconcile the oppofite experiments of Priestley and Scheele.

Upon whatever principle vegetable circulation is conducted, it is certain there is an acefcent juice or fluid which circulates from their roots; this being expofed within the power of the air's attraction it decompounds it, and makes it foul air the fame as animal refpiration. This vegetable juice or fluid has equally the fame effect out of the veffels as in the vegetable, the fame as the animal fluids or blood, which equally decom pounds the air when expofed either out or in the veffels. The vegetable fluids being ftrongly acefcent in their circulation decompound the air (agreeable to the chemical table of attractions) and partly neutralize their acefcency.

The juices received from the earth then attracts phlogiston from the air, and from the rays of the fun, from light, and from the heat, which in the fummer is generally confiderable; they being all concentrated by thofe acefcent fluids. The heavy gravitating earthy parts being attracted by the vegetable fibres are concreted with them, and their principal moisture being evaporated; part of the remaining fluids is fometimes difcharged as a high concentrated fluid in an aerial form, the fame as common air, only of a higher quality. We need not be furprised at this, fince they contain the three great conftituents phlogiston, an acid, and water or earth.

The fun and light have a particular influence upon vegeta tion; for if a vegetable is kept in the dark it will fade, lofing its natural green colour; and its fluids will not have that highimpregnation of phlogifton. In fhort it may just be faid barely to vegetate. Dr. Priestley found that light was the great agent which made vegetables form empyreal air, that if they were placed in the dark no air would be generated. Mr. Ingenhouz found that vegetables in the day time would yield empyreal air, but in the night time foul air.

Thefe experiments directly fhew us how neceffary the fun is to vegetation, and to the formation of empyreal air. As the juices circulate within the vegetable they receive a higher impregnation of phlogifton or quiefcent fire; fo at laft their impregnation is fo high as to expand the fluids, and give them an aerial form, and agreeable to that obfervation of Mr. Ingenhouz, in the day time the impregnation is fo high as to form empyreal air, but at night, being bereft of the fun, it forms only foul air.'.

If this means any thing, it is, that vegetables are capa ble of producing air, because they contain all the ingredients of the combination, when joined with the heat of the fun. Yet the author afterwards tells us, that if he is confirmed in one fact in this work' it is, that vegetables make the air foul. He informs us, indeed, that he avoided the aquatic plants in

his experiment; but we can tell him, that no plant affords pure air, except it be in a healthy ftate, and the quantity of air is in proportion to its ftrength and vigour. If then he tried the experiments in the ufual way, he would find the air injured by almoft every plant, except an aquatic; for every other muft be forced from its natural fituation before the experiment can be tried. Perhaps there is no fact better afcertained, than that healthy ftrong plants, in the fun, really feparate pure air. We fhould be glad to be informed by our author, howevery particle of air' can be expelled from water; and next, how the water can be prevented from re-absorbing air from the atmosphere, in fuch experiments? Neither boiling, nor the air-pump, will be fufficient; for after all thefe experiments, we are able to demonstrate air in water, by unequivocal experiments, though the water be not decompofed.

The nature and formation of pyrophori are explained on the author's general principles, viz. a large quantity of neutralized heat, flightly connected. But few will probably agree with him in thinking, that the heat of the fun is the cause of the faltness of the fea.

The fun being the great author of fire, his rays upon this globe being concentrated, form fulphur, oils, bitumens, falts, &c. Upon the earth his rays form vegetation and animal life. Upon the immenfe waters the falts of the fea and animal life; for as there is no vegetation there comparatively, his rays are neutralized by the waters, and form the falt fluid. It is from this caufe that the fea has the greatest degree of faltnefs immediately upon that part of the globe where the fun is vertical, and in the autumn after he has given his full influence."

We have felected this paragraph, not only to fupport our affertion, but to enter the strongest protest against this mode of philofophifing.

$

Our author's opinion of heat, and its combinations, are already known the tenth and eleventh chapters explain them more fully; and various arguments are adduced, we think without fuccefs, to fhew that the caufticity of earths and falts do not depend fo much on the absence of fixed air, as on the prefence of neutralized and concentrated heat..

The following chapters are chiefly an account of difficulties, which, in our author's opinion, attend the common fyftems. We own that there are many difficulties in the aerial philofophy; but our author has magnified them, by not attending to fome neceffary distinctions, and increased them by his errors. He feems to think, however, that phlogifton is not attracted by air, but that it is neutralized by acids. The abforption of air by metals, in calcination, was known by Dr. Hales: it

*has

has not yet been proved, that the air abforbed is only the de phlogisticated portion of the atmosphere, which we now know to be a very inconfiderable part of it, perhaps not exceeding one-third.

The next chapter is entitled Some ftriking Facts and Obfervations. The facts are chiefly collected from fome modern chemical works, and explained by our author's theory. They relate to the formation of empyreal air, which leads to the method pursued by nature to correct vitiated air. We here

find that, at last, our author really thinks that this is not per formed by vegetation. It is enough to remark, that this theory neceffarily fuppofes impure air lighter than common air; in fact, fixed air is heavier, and phlogifticated air differs fo little, that a common hill brings us into an atmosphere of the fame weight. The difference is fcarcely 3000

We then meet with fome obfervations on the electric matter, as forming different kinds of air.' It is fuppofed, that the matter is the fame with phlogifton. The author concludes with fome of the different theories relating to the formation of air, with obfervations on each, and an attempt to show the fuperiority of his own fyftem.

We have confidered this volume more particularly than may have feemed neceffary from its appearance, because it was our duty to examine whatever had pretenfions to novelty, or tended, in the flighteft degree, to improve our knowlege in thefe intricate difquifitions. Yet the form prevented us from being very full on any part; for the work is often vague and defultory, truth is mixed with error, and though it refts, in a great degree, on the experiments of others, is not free from mistakes and mifreprefentations. This was fometimes unavoidable, fince this writer has, confeffedly in one inftance, and probably in more, examined fyftems, of which he has only feen imperfect extracts. All these circumstances prevented a more exact analysis; but we must again repeat our commendations of the author's ingenuity, which, though fometimes confpicuous in investigating truth, has been frequently an ignis fatuus which has led him into error.

Medical Transactions, published by the College of Phyficians in London. Vol. III. 8vo. 6s. in Boards. Dodiley. AFTER repeated efforts, the College have concluded their Volume; and indeed, in every part of it, the labour and the difficulty are confpicuous. But we must explain. The fecond volume appeared in the year 1772, and was mentioned in the thirty-third of our Journal: three years afterwards a pamphlet, confifting of about four sheets, was published, under

the fame title, as it was faid to be uncertain when the Col lege of Phyficians would go on with the defign of publishing medical papers. This pamphlet is now re-publifhed, as the defign appears to be continued; though it would not have detracted from their dignity, if the remainder of the volume had appeared feparately, efpecially for the purchafers of the former part à refpectable fociety fhould not defcend to the artifices of a profeffed book-maker. We fhall confider the whole, as ufual, in its order, for we did not examine the first part, at the time of its publication.

Article I. A Letter to Dr. Heberden, concerning the Angina Pectoris; and Dr. Heberden's Account of the Diffection of one who had been troubled with that Disorder.-This is the narrative of an intelligent man, who had carefully obferved the progrefs of his difcafe, and related it with fidelity and diftin&iness. It appears to us a valuable model of what medical narratives should be. The complaint is now better known in its form, than the method of cure. The latter has certainly been obfcured, by other difeafes having been miftaken for the angina pectoris: confequently the successful remedies in thofe complaints muft fail, when applied to the real disease. It has not yet been remarked, how little the name is applicable to the fymptoms, which are frequently owing to a fpafm of the external muscles, though certainly combined with a fimilar affection of the bronchial fibres, and the heart. We fhall felect the diffection, which, as usual, rather fhows the effect than the cause of the disease.

In general the vifcera were well formed, and in a found ftate, with marks of great robuftnefs. The contents of the thorax were examined with peculiar attention, particularly the heart with its veffels and valves, and were all found to be in a natural condition, except fome few fpecks of a beginning offfication upon the aorta, and fome adhesion of the lungs to the pleura on the left fide. The left ventricle of the heart was remarkably ftrong and thick, and as perfectly empty of blood, as if it had been washed. Nothing extraordinary could be perceived in the brain, unless that there was rather more water in the ventricles, than is common for fuch an age. It was very remarkable, that the blood was no where coagulated, and did not coagulate even after being more than two hours exposed to the air; but at the fame time could not be called perfectly fuid; being of the confiflence of thin cream; but there was no feptration of any of its component parts.?

We shall felect alfo the diffection of Dr. Wall's patient, which contains every thing remarkable in the fecond Article. Upon attempting to open the thorax, the cartilages of the ribs were found fo much indurated, that it was exceedingly

difficult

difficult to divide them by the knife. This offification was mat remarkable in the fixth rib on each fide, but was much the ftrongest on the left; being there full as hard as the bone itfelf.

Upon raising the sternum, the furface of the pericardium for a large extent was covered with fat, nearly an inch in thickness. The lungs were greatly diftended with very black blood, they were full and hard; and in the cavity of the thorax was a very confiderable quantity of an aqueous fluid.

Upon cutting into the lungs, a frothy mucus, mixt with fomething purulent and of a foetid fmell, iffued from every part, but principally from the divided bronchia: this matter was more in quantity from the left lobe; but no cavity, ulcer, or abfcefs, were obferved any where.-Upon opening the pericardium, the heart appeared of an uncommon fize, and was covered with a great quantity of fat; the pericardium contained not lefs than a pint of fluid. Upon examining the heart, no part appeared difeafed, till we opened the left ventricle; and there, the femilunar valves, placed at the origin of the aorta, were found to be perfectly offified. They did not, as ufual, lie fat the divided orifice of the veffel; but flood erect, and upon appeared to be immoveable. They were entirely offeous through their whole fubftance; but the offification was formed unevenly, and as it were in fpines, fome parts being near a line in thickness, and others thin like a connecting membrane, but perfectly boney. The aorta was at its curvature confiderably enlarged; and for near an inch from the heart, was in part offified; there being feveral bony fcales or laminæ in it, but not connected with one another.'

In this cafe, the induration of the valves must have been the effect rather than the cause. We have been informed that it is not an uncommon appearance, in the bodies of those who have died of angina pectoris.

III, Cafes and Remarks relative to Difeafes of the Bones; by Mr. Walker, Surgeon, in Virginia. In the principal cafe contained in this article, the cavity of the humerus was laid open by fucceffive applications of the trepan. The bone was carious, and the rotten parts exfoliated, fo that the boy recovered the use of his arm.

IV. The Confequences of a Crown-Piece, fwallowed by an Epileptic Man.The crown-piece had been swallowed during an epileptic fit, and was afterwards brought up in confequence of violent vomiting. The epileptic fits ceased; but this mode of cure is not likely to become popular in fact, the whole article is exceedingly trifling.

V. The Method of preparing the Ginfeng-Root in China. This paper is fomewhat more valuable than the laft, but contains nothing fufficiently interesting, to induce us to felect any part of it."

VI. A