highly rectified fpirit of wine, oil of olives, or oil of vitriol, no flinty cruft was formed; and that it appeared only when there was water in the receiver. Mr. Forfter likewife, in his inftructions, confiders Quartz (one of the flinty ftones) as a compound confifting only of this new acid and fteams of water meeting together; and thinks it highly probable that even the diamond is formed of the moft fubtile fteam of water, united with this particular acid.

It may however be fuggefted, by thofe who find it difficult to conceive that flints and diamonds are compounds only of acid and water, that the ftoney matter, that appears on the surface of the water in the above-mentioned procefs, may poffibly have been fublimed, in that form, from the mafs in the retort.-But it would be equally inconvenient and unfair for us to enforce any doubts of this nature, against the juftice of the preceding inferences, as we have not room to give, at full length, all the experiments and their circumstances, from which they are deduced. We shall only therefore once more refer the curious to the original: at the fame time, however, recommending to their confideration the contents of a paper of Mr. Marggraf's, published in the 24th volume of the Berlin Memoirs (and of which we gave a fhort account in our laft Appendix +) on the Volati lifation of the Flus-Spaht; which may poffibly throw fome light on this curious fubject.

We shall finifh our account of this fmall but useful and interesting publication, by adding the purport of an advertisement annexed to the preceding paper; in which Mr. Forfter informs us that Mr. Scheele, Prof. Torbern Bergman, and Mr. J. G. Gahn have lately, by a feries of curious and interefting experiments, fucceeded in analyfing and regenerating various mineral fubftances, and particularly Zeolites, Garnets, Cockle, Quarts, Feld-Spar, or Rhombic Quartz, Soap-rock, or Soap-stone, and Blacklead; and that the refult of their difcoveries will be publifhed in the Memoirs of the Swedish Royal Academy of Sciences; 'by which means a new light will be thrown on Mineralogy; and the claffification of foil fubftances will be greatly facilitated. We fhall only add that the prefent pamphlet is terminated by fome useful notes and additions to Cronstedt's Mine- ralogy, by Prof. M. T. Brunnich.

ART. XI. A Treatife on the medicinal Virtues of the Waters of Aix la Chapelle and Borfet. The whole drawn from a Chain of phyfical Reafoning upon their Nature and Effects, &c. To which is added, A Chemical Analysis of the Waters, from a Number of Experiments made on the Spot. By J. Williams, M. D. 8vo. 4 s. fewed. Becket. 1772.

F the many treatifes that have been published relative to thefe celebrated waters, the prefent publication appears to us to contain the most rational and fatisfactory account of their nature and effects on the human body, afcertained by actual experiment and obfervation. The late very ingenious Dr. Lucas was, we believe, the only perfon who attempted to investigate the true nature and contents of thefe medicinal springs in a scientific manner, and on true chemical principles: but it appears, from the prefent Author's account, that this excellent chemift was, in many inftances, impofed upon by the members of the faculty and others refident at Aix, who thought it was their intereft to deceive him ;' and whofe principles and practice, as reprefented in this work, are fuch as give us no very high idea or opinion either of their honefty or understandings.

With refpect to the firft, we need only to mention the charges urged by the Author against many of the phyficians at this place, who are generally recommended to the ftrangers that arrive here by the refpective masters of the great bathing houses; and who accordingly make it a rule to recommend, in return, the houfes or baths of their good friends: although they are confcious of the great inferiority, in ftrength and efficacy, of the baths which they patronize on fuch felfifh and unworthy motives. Several inftances are here given by the Author, to prove the juftice of this obfervation.

As to the difcernment of thefe medical fages, we shall only obferve, that, in feveral of the cafes here related, we fee thefe worthy difciples of Dr. Sangrado, improving on the practice of their great mafter, and not only indifcriminately drenching all who prefent themselves, without regard to the nature of the difeafe, or the conftitution of the patient; but likewise, in many cafes, where the ufe of the waters might be proper, obviously counteracting and defeating their falutary powers, by a concomitant and uninterrupted courfe of draftic and debilitating purgatives, procured from the fhops. We give these hort hints merely with a view to excite thofe who peruse our journal, and who may be interested in this subject, either as physicians or patients, to confult the work itself; from which they may extract fome ufeful information relative to the intrigues practifed at this celebrated and much frequented watering place; where, according to the Author's repeated affer

tions, the healths of many are facrificed to felf intereft, ignorance, and a long eftablished and abfurd routine.

The analyfis, and the obfervations relating to the effects of thefe waters, were made by the Author upon the fpot; where he was countenanced in the profecution of thefe enquiries by fome of the burgomafters and principal inhabitants of the city, who were defirous that the world fhould be rightly informed of the medicinal virtues of their waters, and be judges for themselves, in a matter which muft evidently be effential to many a diseased perfon, and which may likewife not a little contribute to the intereft of the state.'

Though we cannot follow the Author throughout his ches mical analysis of thefe waters, we shall flop to collect a few particulars relating to a curious and much contraverted chemical question intimately connected with it: we mean the en quiry whether thefe medical fprings really contain that particu lar principle, with which they, and the other waters of the fame clafs, are fuppofed to be impregnated; and to which they owe their diftinguishing title or epithet of fulphureous.

It is affirmed by many, that mineral waters of this kind contain an actual fulphur diffolved in them; and a late French analyfer of the waters of Aix la Chappelle, in particular, has endeavoured to prove that a portion of that mineral is actually diffolved in them. The Author, however, though he repeatedly obferves and acknowledges, that more or lefs real fulphur is found in all the vaults of the clofe covered fources, and in many of the aqueducts that convey thefe waters from the great fource to the different baths, and that the faid fulphur is undoubtedly the product of thefe waters; yet he abfolutely denies that they contain a fingle particle of that mineral. We cannot here defcribe the different experiments produced in proof of this affertion, nor difcufs how far they are decifive: but fhall obferve, that the feeming contrariety that prefents itfelf between his acknowledgment that fulphur is actually fublimed from these waters, and his affertion that they contain no fulphur, vanishes on attending to this diftinction; that though thefe baths are not impregnated with real fulphur, yet they evidently contain the vitriolic acid and phlogiston, the two component principles of that mineral; each of which fingly rifing in the form of vapour, afterward unite and condenfe on the adjoining bodies, and, by this union, conftitute the real folid fulphur which may be collected from them. In short, these waters, according to the Author's idea, may he said, if we may be allowed the expreffion, to contain fulphur virtually or potentially, but not actually or fubftantially On this occafion we hall offer, merely by way of illuftrating the Author's opi

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nion,

nion, an inftance that occurs to us of a fimilar production of this fame concrete, from a body which cannot properly be faid to have contained it à priori.

That curious chemical production, ufually termed Homberg's Phosphorus, or more properly Pyrophorus, which takes fire immediately on being expofed to the air, confifts, as is well known, only of a vegetable or animal coal, mixed with alum, or (as M. de Savigny has fince fhewn *) with fome other vitriolic falt, both reduced to a powder, which is afterwards fubjected to a confiderable degree of heat in a matrafs. Before this powder is exposed to the fire, it cannot properly be faid that the mixture contains fubftantially a fingle grain of fulphur. It contains, however, the vitriolic acid in the alum, and the phlogiston in the charcoal. By the heat applied, these two principles, poffibly before any fulphur is formed in the matras, rife up to the mouth of it, and by their union conftitute an actual fulphur, which may be collected there; and the prefence of which may be otherwife, and more eafily, afcertained by the appearance of the fulphureous flame always obfervable in the mouth of the vial, during the time of the process.—The circumstances, we must obferve and acknowledge, are not the fame in the two cafes: accordingly we mention these appearances, not as a proof of the juftice of the Author's hypothefis; but merely as an illuftration of his manner of accounting for the generation of the fulphur, that evidently appears in the various receptacles or conduits, which receive or convey these waters. To give our opinion on this fubject in the grofs, we fhall obferve, that the Author's experiments do not appear to us fully to prove that these two principles may not have been actually united in the waters at Aix, as they are found to be in the phofphorus, at the end of the process; and that it is very poffible to prepare an artificial folution of fulphur in water, which will ftand the tefts here applied to thofe of Aix la Chappelle.

After having given the analyfis of thefe waters, which, however, is rendered fomewhat incomplete by the Author's either not being acquainted with, or at least overlooking the probable inftrumentality of fixed air, as a menftruum or folvent of the folid contents of mineral waters; and after having deferibed the various baths, which differ very confiderably in ftrength and efficacy, by the loss of their volatile principles, in propor

In the Third Volume of the Collection of Memoirs, prefented by the Correfpondents of the Royal Academy of Sciences at Paris; where an ingenious and very plausible theory of this extraordinary procefs is given.

tion as they recede from the original fources, the Author treats very particularly of the medical virtues of thefe fprings, and defcribes thofe diforders which they are qualified to relieve, as well as thofe in which the ufe of them is undoubtedly pernicious. His obfervations on thefe heads, are founded not only on the medical qualities of their contents; but on the remarks which he has made on their effects, in a variety of cafes that have fallen under his immediate obfervation, feveral of which are here related. On the whole, this appears to be a very fenfible and judicious performance; and though the Author's theory may not be every where perfectly unexceptionable, his remarks and directions with refpect to the use of thefe waters, and his hints relating to the management or practices of thofe who difpenfe them, may be highly ferviceable to fuch as, from their fituation and circumftances, may be difpofed and enabled to make trial of their efficacy; as they appear to be the refult of a judicious and attentive obfervation of their good and bad effects, in a great variety of diseases.

ART. XII. Obfervations on the Operation and Use of Mercury in the Venereal Difeafe. By Andrew Duncan, M. D.. Fellow of the Royal College of Phyficians, Edinburgh. 12mo. 3 s. Edinburgh. Kincaid. 1772. Sold by Cadell in London.

THE

HE great and undoubted efficacy of this mineral fubftance, in the cure of venereal diforders, in all their different ftages, render an inveftigation of its real mode of operation, and an enquiry into the best forms of exhibiting it, a matter of very confiderable importance in the medical art. The ingenious Author of this little tract firft enquires into the probable manner in which mercury produces the falutary effects known to attend the exhibition of it. Nothing, he justly obferves, can contribute more to fafe and effectual practice, than an acquaintance with thofe principles on which remedies operate. By fuch a knowledge certainly, founded on experiment, accurate obfervation, and a careful induction, we are enabled to accommodate their ufe to particular circumftances, and, by means of analogy, largely to extend their application to very different diforders.

In the profecution of this enquiry, he controverts the doctrine maintained by many of the faculty, that the good effects produced by mercury, in the cure of the Lues Venerea, are to be afcribed to the evacuation which it occafions. He fhews the infufficiency of the arguments brought in fupport of this hypothefis, and produces many ftrong objections and obfervations, which feem to furnish fufficient grounds to reject it; fuppofing even that no fallacy could have been detected in the arguments ufed by the patronifers of it. He oblerves, in particular,

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that