merfion be produced, directly by the entrance of water into the cavity of the lungs, or indirectly by the exclufion of atmospheric air? On the diffection of animals drowned in a coloured fluid, he found a fmall quantity of the fluid in the lungs. To deter mine whether it had entered during the process of drowning, or by its own gravity after the death of the animal, he plunged, animals who had been strangled, into ink, but, on diffection, found none in the lungs. To eftimate the exact quantity taken in of any fluid that had a disposition to unite with the mucus of the lungs was impoffible; our author therefore chofe quickfilver, and found, on the diffection of animals immersed in it, that only an inconfiderable portion had entered the lungs. In other experiments he obferved that a quantity of water, much greater than that of quickfilver thus found, introduced into the cavity without fubmerfion, did not produce death. From these facts it was obvious to conclude that contending phyfiologifts had divided truth between them; that, as it was on the one hand true, that fome fluid does enter the lungs during the ftruggles of fubmerfion, fo it was, on the other, equally evident that it is not the caufe of death. Having, by thefe decifive experiments, excluded the operation of this fuppofed caufe, he proceeds to confider a more modern and more plaufible hypothefis, which afferts that the obstruction of the circulating blood in the thorax, arifing from its not being dilated by inspiration, is the cause of death in these diseases. This fuppofition is refuted by a series of ingenious and judicious experiments; from which it is inferred that the proportion of the diameter of the thorax after expiration is to its diameter after infpiration as 109 to 123: that when the cavity of the lungs is diminished one third by artificial hyorothorax, the blood continues to circulate freely; that therefore the dilatation of the lungs is not the final cause of respiration; nor does the fufpenfion of that function produce death by mechanical obftruction. His next object is to establish the reality, and determine the nature, of the chemical action of air on the blood in the lungs, which imparts to it properties neceffary to the fupport of life. He fhews that the venous blood in the right heart and pulmonary artery is, by the action of air through the coats of the veffels, changed into florid arterial blood, and paffes into the left auricle and ventricle; and that when, by the exclufion of air, the circulating fluid retains the properties of venous blood, the motions of the left heart ceafe; that with refpect to the conftituent parts of the volume of infpired air, the dephlogisticated air is confiderably diminished by inspiration, the fixed air somewhat increased, and the phlogifticated air remains unchanged. The change in the colour and properties of the blood must either be attributed to the feparation

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of fixed air from it, or to the action of dephlogisticated air upon it. That it depends on the latter caufe is proved from the experiment of introducing fixed air into a veffel containing florid blood, which did not become black; whereas venous blood was changed into florid, both in the body and out of it, by being expofed to dephlogifticated air. Having afcertained these important facts, our author wifely declines entering on the flippery and hazardous controversy between the phlogistic and pneumatic chemifts. He corroborates his conclufion by feveral convincing experiments on amphibious animals: he proves that the inquinated air does not operate on the nerves, nor by any noxious power deftroy the contractibility of the heart; but that, by the diminution of that ftimulating quality which the blood received from the contact of pure air, it is no longer capable of exciting the action of the heart. The proximate caufe of the diseases, which are the object of his inquiry, he therefore concludes to be the prefence of venous blood in the left heart and arterial fyftem. In his nofological fpeculations, which follow this difcuffion, he has been by no means fo happy as in his experimental pursuits. In defining and arranging difeafes by their nature and not by their Symptoms, he offends against the first principle of all systems of nofology. He denominates the afphyxia of former authors, Melanama ex penav spa, fanguis niger; and one part of the definition, impedita fanguinis venofi in arteriofum converfio never. could have been admitted by any correct nofologift.

The author, in the progrefs of his inquiry confiders the means of diftinguifhing thefe difeafes from death; and here we muft confefs we have been difappointed. The object is indeed important, and the author's obfervations are ushered in with fomewhat of the parade of difcovery; but quid dignum tanto feret hic promiffor hiatu." We are informed that, if the means of recovery fail, we are to conclude that the principle of life is deftroyed; but, if thefe means fucceed, the cafe is asphyxia, where the functions of life have been fufpended. Surely this is not very novel or recondite. The cure of these diseases is the laft and most important object of his researches; and here he feems to have attained a degree of certainty and fimplicity on which we may congratulate the friends of fcience and humanity. The effectual and eafily acceffible remedies, which à decifive experience authorifes him to recommend, are, the application of heat to the furface of the body, and the introduction of air into the lungs; for which he defcribes a commodious and ingenioufly-contrived apparatus. Thefe are, in his opinion, the best means of exciting the latent vital energies; and the other remedies which have acquired reputation, he pronounces (apparently with good reafon) to be either inert, dangerous, doubtful,

or as operating in a tedious and circuitous manner, unfit to be used in a disease where delay is certain death.

We have thus given (what we conceive to be peculiarly proper in experimental works) an analysis of the volume before us. The attempt to give our readers a clear though abridged view of the whole, has made it impoffible, confiftently with our limits, to detail any of the experiments.

ART. VII. Experiments and Obfervations to investigate, by Chemical Analyfis, the Medicinal Properties of the Mineral Waters of Spa and Aix-la-Chapelle, in Germany; and of the Waters and Boue near St. Amand, in French Flanders. By John Afh, M. D. Fellow of the Royal College of Phyficians, of the Royal Society, and of the Society of Antiquaries. Small 8vo, 4s. boards. Robfon and Clarke. London, 1788.

THE

HE analyfis of mineral waters being entirely dependent on chemistry, it is impoffible to attain an accurate knowledge of their compofition, unless by the means of that science. The late discoveries in chemistry, however, are fo numerous and important, and fo repugnant, in many inftances, to the principles formerly maintained, that a great part of the deductions which were founded on those principles is now proved incontestibly to have been erroneous. It is therefore of great confequence that an accurate revifal fhould be made of the more celebrated mineral waters, in order that their real nature may be duly afcertained, and every error, which might lead to a mifapplication of their virtues, be exploded. In the treatise now before us Dr. Afh appears to have been actuated by this motive; and he has purfued his inquiry with much attention.

After a long introduction, abounding with chemical knowledge, the author proceeds to give an account of the mineral waters of Spa; which we may fafely affirm to have been treated of, however imperfectly, by at least a hundred preceding

writers.

The town of Spa is fituated at the extremity of a winding valley, on the banks of a rapid rivulet, and is well sheltered by an adjoining hill to the north, and a high ridge of mountains encircling it, at the distance of a mile to two miles and a half from the fouth-eaft quite round to the north-weft. Only one of the Spa fountains, the Pouhon fpring, fituated nearly in the centre of the town of Spa, rifes from the hill to the north of the town, and clofe adjoining to it; a hill confifting of argillaceous fchifts, loofe argillaceous fubftances, and earths mixed with ferruginous flate, in large maffes; whereas all the other

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feven fountains have a northern aspect, rise on that fide of the encircling ridge of mountains to the fouth-eaft, fouth, west, and north-weft, from the town; and this ridge of mountains is formed, in large maffes of calcareous ftones, and marbles, and other mineral bodies, mixed with loose filiceous earths and ftones, and whofe tops are covered with woods, interfperfed with large boggy fwamps, filled with water and mud. The most diftin, guifhed mineral fountains, within the diftrict of Spa, are, the Pouhon, Geronftere, Sauviniere, Groifbeeck, and the Tonnelet; to which may be added the less frequented fprings of the Niverfct, the Watror, and the Barifart. The following is the author's general account of the moft celebrated of these medicinal frings:

The Pouhon fountain is to be regarded as the principal fpring at Spa, both as it is most abundant and powerful in the quantity as well as the quality of its iron, and as it retains, longer than any of the other springs, its fpirituous gas, and of confequence its iron alfo. The other fountains differ from the Pouhon in their general contents, as they all have lefs fpirituous gas, except the Tonnelet, which contains it in greater abundance than any of them, even the Pouhon; and they all contain lefs iron, and, in part, a different kind of abforbent earth. The Tonnelet is much purer than the others, and is impregnated with less of the other contents, as well as iron, than any of the others; and its elaftic gas is more volatile and fugacious than that of all the others.

The Geronftere fountain is ftill more fingular, as it is the only one of them that fenfibly discovers any hepatic air to be contained in it. The Groifbeeck fountain has been celebrated, through a Jong fucceffion of years, for its good effects in the relief of diforders arifing from calculous concretions in the kidneys or bladder of urine; and a fingular infcription upon it records the cure of a German baron, in the middle of the lalt century, in a fimilar cafe as is fuppofed; in remembrance of which, the fountain is called by his title of Groifbeeck; and that his defcendants erected the ftructure that enclofes the fpring, in gratitude for the extraordinary cure their anceftor had received through the use of this water.

The Pouhon water, as was before said, preferves its spirituous gas much longer than any of the other waters here, and much longer than the generality of gafeous ferruginous waters in common do, And, as the aerial acid remains fo long tenaciously united to the iron, after expofing them for a confiderable time in a fhallow veffel to the open air, although the gas appears, by the lofs of the quick lively taste in the water, by degrees to escape, it will be fome time longer before the iron will begin to precipitate, and that very flowly, fo perfect is the union of the iron with the aerial acid in this water.

And both thefe circumftançes contribute to render this chalybeate water fo capable of being fent to great diftances from the fountain, and by proper management to be kept in high prefervation for many years

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years. The reverfe of all this will be found to be the cafe with most of the other waters near Spa, but particularly fo with the water of the Tonnelet, which may almost be deemed a fimple gafeous water; fo fmall is the quantity of any foffil body held in fufpenfion by the aerial acid in it, and fo fugitive is the aerial gas, that it begins to pafs off, and very rapidly, the moment it is taken out of the well, and will all efcape in a very short time.'

Dr. Afh has endeavoured to afcertain by experiment the quantity of aerial acid which enters into the compofition of each of the principal springs at Spa; and points out in what manner, under proper regulations, the quantity of it, as well as the efficacy of its powers, might be increased; or in what manner fo useful a part of them might be detained longer in action upon the other parts of their compofition, whereby the several fubftances held in folution by the means of this acid would be alfo increased, or by proper conftructions of the buildings enclosing the fountains, the degrees of preffure would be advanced, and lefs of this volatile elaftic vapour would efcape; whence lefs of the other contents would be precipitated from the waters to the bottom of the well before they are administered to those who drink them.

The experiments of this author fully establish the alkaline nature of the Spa waters, notwithstanding they are impregnated with aerial acid; and many of them contain it in greater quantities than can be communicated to water by artificial means. On this account, the waters of Spa, particularly that of the Pouhon spring, are remarkable for the qualities of a mild, but active and powerful tonic.

The waters of Aix-la-Chapelle are ascertained by various experiments to be likewise of an alcalefcent quality. In examining this water by evaporation, it appeared that from 70.50 cubic inches of the water taken at the Emperor's bath, and raised from the bottom of the fource, 58.50 of the refiduum were collected, and, when properly treated, yielded of aerated lime 14.50 grains, of aerated mineral alkali 30.75, and of falited mineral alkali 13.25.

The waters of Bordfcheit, or Borfet, rife in the neighbourhood of Aix-la-Chapelle. On these waters Dr. Afh appears to have made only a few experiments; but he had no reason to apprehend any material difference between them and the former with regard either to the nature or quantities of their feveral

contents.

The waters of St. Amand, in French Flanders, are evidently fulphureous. On precipitants being mixed with them they dif covered not the smallest traces of any folution of iron. Dr. Afh, however, very properly obferves that it might be fo fubtilely

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