at confiderable length, his account of medicines in general is neither large, nor diftinguifhed by any pofitive information dif ferent from what is to be found in the other modern systems of the Materia Medica. His opinion, however, is always delivered with an ingenuous freedom, characteristic of great experience; and where he happens to diffent from the authority of others, we are fatisfied that his remarks are more the refult of accurate observation and an unbiaffed judgment, than of any affectation of novelty. For the gratification of our readers, and as a fpecimen of the work, we fhall prefent them with an extract from the article on camphire, concerning the medicinal nature of which fo many various and contradictory opinions have been entertained:

The oppofition of opinions appears ftrongly from hence, that the controverfy has been commonly brought into the fingle question, Whether camphire be a heating or a cooling medicine with respect to the human body? or, as I would put it in other words, Whether it is a ftimulant or a fedative power? The queftion has been often attempted to be determined by frivolous and ill-founded theories, both on one fide and the other; but these fhall be here entirely neglected, as we judge the question must be abfolutely determined by experiments made upon the human body, affifted, however, by fome analogy, wherever it can be fafely drawn, from experiments on brutes.

To this purpose we remark, in the first place, that camphire taken into the mouth is of an acrid tafte; and though, by its evaporation, it excites a fenfe of cold air, what remains is a fenfe of heat in the mouth and fauces; and when taken down into the ftomach, it often gives fome pain and uneafinefs, which we impute to the operation of its acrimony upon the upper orifice of that organ. Thefe may be confidered as marks of its heating quality; and the fame are more ftrongly marked by its application to any ulcerated part, which it always evidently irritates and inflames.

Thefe are indeed marks of a ftimulant power; but hardly any thing correfponding to thefe appears upon its being thrown into the tomach of man or brute animals. It appears that in the ftomach of animals it operates there by a fmall portion of its effluvia; for when a mafs of any bulk has been thrown in, though it has produced conderable effects upon the body, neither the bulk nor weight of what had been thrown in are found to be fenfibly diminished; and in fuch cafes it cannot be doubted that the operation has been entirely upon the nerves of the ftomach, and by these on the rest of the fyftem. This operation cems to me to be entirely that of a sedative power; and we take its being of that kind on the ftomach itfelf, which occafions the indigeftion of the food which has been contantly obferved to follow its exhibition in any large quantity.

• The fedative effects, however, are ftill more evident and confidcrable in the fenforium. The death of fo many animals, fuddenly ccafioned by it, in the experiments of Menghin, can be explained

in no other way but by the power of this fubftance, like that of other poisons, in deftroying the mobility of the nervous power, and thereby extinguishing the vital principle. It is in illuftration of this that it fo often operates by firft inducing ftupor and fleep; and the other fymptoms of delirium, furor, and convulfions, can all be probably explained as we have done with refpect to other poifons, by the struggle that occurs between the force of the fedative power and the reaction of the fyftem.

The

But before we go further, it is proper to inquire what are its effects on the fanguiferous fyftem. And here at least we can affert that it thews in the first inftance no ftimulant power. I regret that in the account of the experiments on brutes that we have met with, there is no mention of the ftate of their pulfe; but I think we kave enough of experiments on men to afcertain this matter. experiments of Hoffman affure us that the pulfe was not rendered more frequent, or the skin warmer, by twenty grains and upwards of camphire being taken into the ftomach. The experiments of Griffin and Alexander rather fhew that the frequency of the pulfe was diminished by large dofes of camphire. To thefe we may add the experiments of Berger, Werlhoff, Laffone, Home, and efpecially thofe of Collin.

The laft, in giving fome hundred inftances of the exhibition of camphire in large dofes, even to the quantity of half an ounce in the course of one day, has not, in any one instance, taken notice of the frequency of the pulfe, or of the heat of the body being increased by it. In the cafe in which half an ounce of camphire had been exhibited, the patient was examined by the Baron Van Swieten, and fome other phyficians, who could not mifs to have taken notice of its heate ing the body, if any such effect had appeared. I myself have frequently given twenty grains of camphire, without ever finding the frequency of the pulfe increased by it, and fometimes manifeftly di

minished.

1

• I once had a maniacal patient, a young woman between twentyfive and thirty years of age, whom I was refolved to try the cure of by camphire; and beginning by five grains for a dofe, and increafing it by the fame quantity every evening, I brought it at length to a dole of thirty grains; and that dofe in imitation of Dr. Kinnear, I repeated for four nights together. During all this I never found the frequency of the pulfe increafed; and when the larger defes were employed, the pulfe was frequently brought to be ten ftrokes fewer in a minute than it had been before. At the fame time, fő little change was made in the flate of the mania, that I was refolved to give up the trial; but the apothecary, by a grefs error in Baddam's abridgment of the Philofophical Tranfactions, was led to think that I had mistaken Dr. Kinnear's practice, and bad not carried the dole of camphire fo far as he had done. Proceeding upon this fuppofition, he prefumed to give forty grains of camphire for the next. night's dofe. In about half an hour after this had been exhibited, I was fent for to fee my patient; who, after beating upon her breajk if she had felt fome uneafinefs there, had fallen down feemingly in a faint. She appeared to me quite infenfible, with her pulfe very C 3 weak,

weak and hardly to be felt, and her breathing hardly to be obferved, with a palenefs and coldness over her whole body. I judged her to be dying; but by holding some spirits of hartfhorn to her nofe, and chafing her extremities with warm fiannels, fhe was fo far recovered as to fwallow a little warm milk, and afterwards a little warm wine; and, by these measures continued for two or three hours, her pulfe and the heat of her body were a good deal recovered, and she had the appearance of being in a fleep, in which fhe was allowed to continue till morning, when the came out of it by degrees, with her pulfe very much in its natural ftate. At the fame time the mania was alfo in the fame flate as before, and continued to be fo for fome months afterwards, when I ceased to inquire after her.

Dr. Hoffman gives us the hiftory of a person who, by mistake, took at one draught two fcruples of camphire, which occafioned violent diforder; but the operation was at firft like that in the cafe above mentioned, a weakness and palenefs of the whole body, which evidently fhewed a fedative operation.

From fo many experiments directly in point, I fhall be surprised if any body fhall deny the fedative and affert the ftimulant power of camphire; and when I find Quarin giving the following account,

Vidi enim (he fays) in multis, quibus camphora majori dofi ex•hibita fuit, pulfum celerrimum, faciem ruberrimam, oculos torvos, inflammatos, convulfiones et phrenitidem lethalem fecutam fuiffe," 1, who in an hundred inftances of the exhibition of camphire, both in fmaller and larger dofes, never faw fuch effects produced, muft think that either he or I had our fenfes ftrangely biaffed by preconceived opinions of the ftimulant or fedative power of camphire. I am, however, the more difpofed to truft to my own fenfes, because I have frequently had my fellow-practitioners concurring with me in the fame perceptions.'

We are perfuaded, with Dr. Cullen, that the good effects of the preparations of iron have been often miffed by their being given in too fmall dofes; but we are a little furprised to find that his experience has differed so much from our own with regard to the dofes of those medicines. While he has hardly found any ftomach that would bear two drachms of any chalybeate preparation in one day, we, on the contrary, have found few which could not bear double, or even three times that quantity, with great cafe. We have known it taken in the quantity of three drachms at a dofe, which was repeated thrice a day; fo that within this fpace the patient took nine drachms; and we have little doubt that a larger dofe might have been administered without producing an irritation of the ftomach. Sometimes a flight tendency to a watering of the mouth has been perceived, but unattended with any degree of sickness; and the only fentible effect produced by the largest dofe, was a more plentiful discharge than ufual of limpid urine, which fhewed the kidnies to be affected with a fpafmodic conftriction, The result

was

was the fame, whether the iron was taken in substance or ruft; nor could there, from the usual diagnostic in those cafes, be any reason to doubt that the mineral was partially at least, if not totally, diffolved in the ftomach.

Before we difmifs this work, we muft ingenuously acknowledge that we have reaped great fatisfaction, not without fome disappointment, in perufing it. We had expected that it would have formed, of itself, a complete fyftem of pharmaceutical science, independently of any reference to other fubfidiary pub-lications on the fubject. The author's remarks, likewife, though always well-founded and judicious, are frequently not decifive in any juft proportion to his attentive obfervation and experience; and we think that he fometimes difcovers fuch a degree of candour in diffent, and of diffidence in affertion, as almoft amount to a preclufion of any pofitive inference. The work, however, may juftly be confidered as a most valuable inquiry into the virtues of medicinal substances, as well as an admirable fyftem of physiological and pathological obfervations. Nor can we refrain from congratulating the medical world on the appearance of a publication which tends fo much to fix the ftandard of practical knowledge in medicine, and which is fanctioned by the venerable authority of this learned and celebrated profeffor.

ART. VII.

Philofophical Tranfactions of the Royal Society of London, Vol. LXXVI. For the Year 1786. Part II. 4to. 8s. 6d. fewed. Davis. London, 1786.

THIS part of the annual volume is more than commonly in

terefting and important; but the number of other publications which demand our attention will not permit us to give fo minute an account of the feveral articles as otherwife the fubjects might claim. The firft in this continuation is

Art. XIV. New Experiments upon heat. By Col. Sir Benjamin Thompson, Knt. F. R. S. Sir Benjamin Thompson's object, in this inquiry, was to afcertain what power a vacuum had in conducting heat; and he chofe for the purpose the most perfect vacuum, that of Toricelli, made by the affiftance of mercury, entirely freed from air by boiling in the tube. Though his contrivances were ingenious, but almoft univerfally attended with one objection, which is, that the exhausted tube touched in fome point the tube of the thermometer; or the communication was made through a medium, the conducting power of which was greater than that of glass. Even with this imperfection, however, it appeared that the vacuum was a worse conductor than air; fo that, a fortiori, if it were poffible entirely to infulate

C 4

the

the thermometer, it would probably be found to conduct heat ftill more imperfectly.

Colonel Thompson tried likewife the conducting power of fixed air; but his experiment at firft failed, from his not being aware of the expanfile power of that clement; which is fo great that it is found to expand almoft twice as much as common air. On the whole, the colonel's experiments are not decifive on any point; but he has opened a profpect to an inquiry which may afterwards prove more fuccefsful.

Art. XV, Hiftory and Diflection of an extraordinary Introfufception, By John Coakley Lettfom, M. D. F.R.S. and A.S. In this introfufception, one of the most extenfive of which we remember to have feen any account, the arch of the colon was inverted, and received into the lower part of the fame gut which forms the figmoid flexure. The ileum therefore was become the refervoir of the faces, and was greatly enlarged by their bulk. The fymptoms attending this cafe appear to have been thofe of a dyfentery only,

Art. XVI. New Experiments on the Ocular Spectra of Light and Colours, By R. Waring Darwin, M. D. Ocular fpectra are the images which remain on the retina after looking attentively on any bright object, and continue, when the eyes are fhut, with different hues and varied appearances, not always permanent, but recursing at intervals. The experiments in this paper are, we think, not entirely new, but they are varied by fubftituting different objects, of different colours, in a diversity of circumftances. In the frt fet of experiments, the fpectrum alternately appears and difappears, or its colours change. When the eye is preffed there is a flafh of light; when a perfon becomes dizzy by turning rapidly round, the objects feem to librate. From thefe facts Dr. Darwin concludes that light does not act by mechanical impulfe, or chemical combination, as thefe phenomena arc inconfiftent with either; but that, in producing thefe fpectra, the retina itself is active. We have extracted the following paflage on this fubject, as much of the author's reafoning depends on what it contains:

It is not abfurd to conceive that the retina may be ftimulated into motion, as well as the red and white mufcles which form our limbs and veffels; fince it consists of fibres, like thofe, intermixed with its medullary fubftance. To evince this ftructure, the retina of an ox's eye was fufpended in a glafs of warm water, and forcibly torn in a few places; the edges of thefe parts appeared jagged and hairy, and did not contract, and become fmooth like fimple mucus, when it is diftended till it breaks; which fhews that it confilts of fibres; and this its fibrous conftruction became ftill more diftin&t to the fight, by adding fome cauftic alkali to the water, as the adhering mucus

was