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at considerable length, his accourit of medicines in general is neither large, nor distinguished 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 dissent from the authority of others, we are fatisfied that his remarks are more the result of accurate obfervation and an unbiased judgment, than of any affectation of novelty. For the gratification of our readers, and as a specimen of the work, we shall present them with an extract from the article on camphire, concerning the medicinal nature of which so many various and contradictory opinions have been entertained:

• The opposition of opinions appears strongly from hence, that the controversy has been commonly brought into the single 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 stimulant or a sedative power? The question has been often attempted to be determined by frivolous and ill-founded theories, both on one side and the other; but these shall be here entirely neglected, as we judge the quettion must be absolutely determined by experiments made upon the human body, affifted, however, by some analogy, wherever it can be safely drawn, from experiments on brutes.

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

These are indeed marks of a stimulant power; but hardly any ahing corresponding to these appears upon its being thrown into the itomach of nian or brute animals. It appears that in the stomach of animals it operates there by a small portion of its effluvia; for when a mass of any bulk has been thrown in, though it has produced conüderable effects upon the body, peither the bulk nor weight of what had been thrown in are found to be sensibly diminished ; and in; such cases it cannot be doubted that the operation has been entirely upon the nerves of the stomach, and by these on the rest of the fyftem. This operation seems to me to be entirely that of a fedative power; and we take its being of that kind on the stomach it. tëlf, which occasions the indigestion of the food which has been conHantly observed to follow its exhibition in any large quantity.

• The sedative effects, however, are still more evident and confiderable in the sensorium. The death of so many animals, suddenly occafioned by it, in the experiments of Menghin, can be explained

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in no other way but by the power of this substance, like that of other
poisons, in destroying the mobility of the nervous power, and thereby
extinguishing the vital principle. It is in illuitration of this that it
so often operates by first inducing stupor and sleep; and the other
symptoms of delirium, furor, and convulsions, can all be probably
explained as we have done with respect to other poisons, by the itrug-
gle that occurs between the force of the fedative power and the re-
action of the system.

• But before we go further, it is proper to inquire what are its
effects on the fanguiferous fyftem.

And here at least we can assert that it thews in the firit initance no stimulant power. I

regret

that in the account of the experiments on brutes that we have met with, there is no mention of the state of their pulse; but I think we kave enough of experiments on men to ascertain this matter. The experiments of Hoffmnan affure us that the pulse was not rendered more frequent, or the kin warmer, by tiventy grains and upwards of camphire being taken into the stomach. The experiments of Griffin and Alexander rather shew that the frequency of the pulse was diminished by large doses of canıphire. To these we may add the experiments of Berger, Werlhoff, Lassone, Home, and especially those of Collin.

• The lait, in giving some hundred instances of the exhibition of
camphire in large doses, even to the quantity of half an ounce in the
course of one day, has not, in any one in tance, taken notice of the
frequency of the pulse, or of the heat of the body being increased by
it. In the case in which half an ounce of camphire had been exhi-
bited, the patient was examined by the Baron Van Swieten, and some
other physicians, who could not miss to have taken notice of its heats
ing the body, if any such effect had appeared. I myself have fre-
quently given twenty grains of camphire, without ever finding the
frequency of the puise increased by it, and fonetimes manifestly di-
minished.

• I once had a' maniacal patient, a young woman bitween twenty-
five and thirty years of age, whom I was resolved to try the cure of
by camphire; and beginning by five grains for a dofe, and increasing
it by the same quantity every evening, I broug?t it at length to a dole
of thirty grains ; and that dose in imitation of Dr. Kinnear, I re-
peated for four nights together. During all this I never found the
frequency of the pulse increased; and when the larger dotes were
employed, the pulse was frequently brought to be ten strokes fewer
in a minute than it had been before. At the fine time, só litile
change was made in the flate of the mania, that I ivas refolved to
give up the trial ; but the apothecary, by a grafs error in Baddarn’s
abridgment of the Philosophical Transactions, was led to think that
I had mistaken Dr. Kinnear's practice, and had not carried the dole
of camphire so far as he had done. Proceeding upon this fuppofi-
tion, he presumed to give forty grains of camphire for the next,
night's dose. In about half an hour after this had been exhibited,
I was fent for to see my patient; who, after beating upon her bread
* if she had felt some uneasiness there, had fallen down seemingly in
a faint. She appeared to me quite infenfible, with her hulle very

weak,

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weak and hardly to be felt, and her breathing hardly to be observed, with a paleness and coldness over her whole body. I judged her to be dying ; but by holding some fpirits of hartshorn to her nose, and chafing her extremities with warm fiannels, she was so far recovered as to swallow a little warm milk, and afterwards a little warm wine and, by these measures continued for two or three hours, her pulse and the heat of her body were a good deal recovered, and she had the appearance of being in a sleep, in which she was allowed to con. tinue till morning, when she came out of it by degrees, with her pulse very much in its natural state. At the same time the mania was also in the same state as before, and continued to be so for some months afterwards, when I ceased to inquire after her.

• Dr. Hoffman gives us the history of a person who, by mistake, took at one draught two scruples of camphire, which occafioned violent disorder ; but the operation was at first like that in the case above mentioned, a weakness and paleness of the whole body, which evidently fliewed a sedative operation.

From so many experiments directly in point, I shall be surprised if any body shall deny the sedative and assert the stimulant

power of camphire; and when I find Quarin giving the following account, • Vidi enim (he says) in multis, quibus camphora majori dofi ex«hibita fuit, pulsum celerrimum, faciem ruberrimam, oculos torvos,

inflammatos, convulsiones et phrenitidem lethalem secutam fuiffe, 1, who in an hundred instances of the exhibition of camphire, both jn smaller and larger doses, never saw such effects produced, muft think that either he or I had our senses ftrangely biassed by preconceived opinions of the stimulant or sedative power of camphire. I am, however, the more disposed to trust to my own senses, because I have frequently had my fellow-practitioners concurring with me in the same perceptions.'

We are perfuaded, with Dr. Cullen, that the good effects of the preparations of iron have been often missed by their being given in too small doses; but we are a little surprised to find that his experience has differed so much from our own with regard to the doses of those medicines. - While he has hardly found any stomach 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 ease. We have known it taken in the quantity of three drachms at a dose, which was repeated thrice a day; so that within this space the patient took 'nine drachms and we have little doubt that a larger dose might have been administered without producing an irritation of the stomach, Sometimes a slight tendency to a watering of the mouth has been perceived, but unattended with any degree of sickness; and the only sensible effect produced by the largest dose, was a more plentiful discharge than usual of limpid urine, which shewed the kidnies to be affected with a spasmodic constriction, The result

was

was the same, whether the iron was taken in substance or rust; 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 stomach.

Before we dismiss this work, we must ingenuously acknow. ledge that we have reaped great satisfaction, not without some disappointment, in perusing it. We had expected that it would have formed, of itself, a complete system of pharmaceutical science, independently of any reference to other subsidiary pub-lications on the subject. The author's remarks, likewise, though always well-founded and judicious, are frequently not decisive in any just proportion to his attentive observation and experience; and we think that he sometimes discovers such a degree of candour in dissent, and of diffidence in affertion, as almost amount to a preclusion of any positive inference. The work, however, may justly be considered as a most valuable inquiry into the virtues of medicinal substances, as well as an admirable system of physiological and pathological observations. Nor can we refrain from congratulating the medical world on the appearance of a publication which tends so much to fix the standard of practical knowledge in medicine, and which is sanctioned by the venerable authority of this learned and celebrated profeffor.

ART. VII. Philosophical Transactions of the Royal Society of

London, Vol. LXXVI. For the Year 1786. Part II. 4to.

8s. 6d. sewed. Davis. London, 1786. THIS part of the annual volume is more than commonly in

teresting and important; but the number of other publications which demand our attention will not permit us to give so. minute an account of the several articles as otherwise the subjects might claim. The first in this continúation 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 ascertain what power a vacuum had in conducting heat; and he chose for the purpose the most perfect vacuum, that of Toricelli, made by the affistance of mercury, entirely freed from air by boiling in the tube. Though his contrivances were ingenious, but almost universally attended with one objection, which is, that the exhausted tube touched in some 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 worfe conductor than air ; so that, a fortiori, if it were poffible entirely to insulate

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

Colonel Thompson tried likewise the conducting power of
fixed air; but his experiment at first failed, from his not being
aware of the expansile power of that clement; which is so great
that it is found to expand almost twice as much as common air.
On the whole, the colonel's experiments are not decisive on any
point; but he has opened a prospect to an inquiry which may
afterwards

prove more successful.
Art. XV, History and Diflection of an extraordinary In-
trofufception, By John Coakley Lettsom, M.D.F.R.S. and A.S.
In this introsusception, one of the molt extensive of which we
remember to have seen any account, the arch of the colon was
inverted, and received into the lower part of the same gut which
forms the sigmoid flexure. The ileum therefore was become
the reservoir of the fæces, and was greatly enlarged by their
bulk. The symptoms attending this cale appear to have been
those of a dyfentery only.
Art. XVI. New Experiments

New Experiments on the Ocular Spectra of
Light and Colours, By R. Waring Darwin, M. D.' Ocular
spectra are the images which remain on the retina after looking
attentively on any bright object, and continue, when the eyes
are shut, with different hues and varied appearances, not always
permanent, but recurring 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 circumstances. In the frit fet of experiments, the spectrum
alternately appears and disappears, or its colours change. When
the eye is pressed there is a flash of light; when a person be-
comes dizzy by turning rapidly round, the objects seem to li-
Þrate. From these facts Dr. Darwin concludes that light does
not act by mechanical impulle, or chemical combination, as
tiese phenomena arc inconsistent with either; but that, in pro-
ducing these spectra, the retina itself is active. We have ex-
tracted the following pallage on this subject, as much of the au-
thor's reasoning depends on what it contains :

* It is not absurd' to conceive that the retina may be stimulated into motion, as well as the red and white muscles which form our limbs and veslels; since it consists of fibres, like those, intermixed with its medullary substance. To evince this structure, the retina of an ox's eye was suspended in a glass of warm water, and forcibly torn in a few places; the edges of these parts appeared jagged and hairy, and did not contract, and become smooth like simple mucus, when it is diltended till it breaks ; which thews that it confilts of fibres; and this its fibrous construction became ftill more distinct to the fight, by adding fome caustic alkali to the water, as the adhering mucus

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