another phenomenon, that has been fometimes gently bending the tongues and pens of our phyfical theorifts towards the profound language, that procured veneration to occult caufes fome centuries ago. It is the doctrine of M. de Buffon, whofe genius is of the comprehenfive and combining kind, that the laws of affinities are the fame with that general law by which the celeftial bodies act upon each other, and that they (affinities) exert their powers in the fame proportions of maffes and distances. Sage, in the year 1773, compofed a table of affinities upon this principle of gravity; but a farther obfervation of M. de Buffon, if it be true, renders this principle inadequate to the phenomena, and confequently uncertain and ambiguous: the observation is, that figure, which in the celeftial bodies has little or no influence on the law of their action on each other, because their distance from each other is great, has an extenfive influence, and does almost all, in the affinities between bodies, whofe diftance from each other is fmall or null. Now this obfervation difconcerts the hypothefis of specific gravity; for if the degrees of affinities depend abfolutely upon the figure of the conftituent parts of bodies, thefe degrees muft, like the figures, vary ad infinitum, even where the Ipecific gravities are the fame. The different operations of different falts on various fubftances, and the different cryftallizations, that are obvious to the eye of an attentive obferver, will not permit our Author to call in queftion this obfervation of M. de Buffon. He affirms, nevertheless, that our perfect ignorance of the figure of the conftituent parts of bodies, which the philofopher of Paris has been fo gracious as to acknowledge, obliges us, in our enquiries after the caufes of particular affinities, to confine our researches to the different proportions and relations which take place between the fpecific gravities of the particular fubftances. That is to fay-we do not know the true caufe, and therefore must take up with fuch a cause as we can come at. Simple affinity is the tendency of two homogeneous bodies to mutual union and cohefion, and the more that the substances are homogeneous, the more powerful is the cohesion or attraction; nor, according to our Author, can there be any affinity between two heterogeneous fubftances, unlefs a third fubftance intervene, which has fomething analogous to, or in common with, them both. It is thus that oil and water may be united by the intervention of an alkali:-It is true, continues our Author, that we frequently fee fubftances, that do not appear to us at all homogeneous, blended together, with eafe, in the most perfect union; but, on clofe inquiry, it will be found, adds he, that thefe fubftances have fome parts that are analogous to each other, and even homogeneous, though in all their other parts. they are heterogeneous in the highest degree. Such are the N n APP. Rev. Vol. Ix. diffolvents diffolvents and chymical menftruums, which act palpably on fubftances with which they seem to have no analogy; but no menftruum, according to our Author, can dissolve a substance, with the principles of which it has no fort of analogy or homogeneity; and if acids act in this manner upon metals, it is because the phosphorus, which is the principle of metallifm (if we may use that term), contains an acid. The relation, then, of analogy or homogeneity, that different fubftances have with their menftruums, and thefe latter with their substances, is what the Chymifts more especially distinguish by the name of affinity, and the different degrees of this relation feem to be derived from the laws of gravity. Our Author therefore treats the subject of affinity, thus defined in its nature, and determined in its degree, by reducing it to two general laws, ift, the relation or analogy of different menftruums to the fame fubftance; 2dly, the relation of different fubftances to the fame menftruum. The detail into which our Author enters in the illustration of these laws is methodical, clear and interesting, and it occupies the first ten letters of this volume. In the eleventh and twelfth he treats of aeriform fubftances, which are known, at prefent, under the denomination of gas. We find under this article, the relation of a fact, which proves, in a very striking manner, the anti-feptic quality of fixed air or the mephitic acid. At Latera (fays our Author), near Bolsena in Italy, a goat which had died in the vapour of a non-inflammable moffet, was obferved to remain found and entirely exempt from putrefaction during the space of five or fix months. " In the two following Letters DR. DEMESTE treats of phofphoric and faline fubftances, with his ufual fagacity; and then proceeds to lithology, or the hiftory of ftones. Linnæus was the first who perceived that there can be no cryftallization without a faline principle, and therefore ranged cryftallized stones in the clafs of falts. Sage generalized till farther the idea of Linnæus, and being convinced by the analytic process, that all the earths and ftones of which our globe is compofed, refult from a combination of one or more acids with an alkaline or terreous bafis, he concluded from thence that they must be real, faline mixts, though void of tafte and favour, and almoft all indiffolvable in water *. M. Romé de L'Ifle, by his cryftallographical observations, has also confirmed this hypothefis, and fhewn the analogy there is between falts and ftones. Our Author adopts the divifion, made by M. Sage, of lithology into fix claffes, but Our Author fays almost all,-for the gypfum or plafter stone, of which there are fuch immenfe quarries, is really, notwithstanding the general opinion, fufceptible of folution in a large quantity of water. does does not arrange ftony fubftances in these claffes in the fame manner with that famous mineralogist.—He describes with the greatest accuracy all the cryftals hitherto known; his defcriptions, indeed, are not accompanied with figures, but he makes amends for this by referring the Reader to those which are to be found in the plates of M. Romé de l'Ifle's excellent essay (as it is modeftly called) concerning cryftallography. Thefe figures our Author points out exactly, and they are of great use in the perufal of these letters, in which the Reader will find new aspects of the proceedings of nature in this branch. Besides, the utility of these cryftallogical researches will appear greater than may be imagined at firft fight, when it is confidered, that they furnifh confequences and refults, which explain the formation of thofe rocks of the granit kind, which the most celebrated naturalifts, at prefent, confider as a mafs that fuftains all the other rocks known to us. This part of the work before us is particularly curious, and in no other does the Author appear more master of his fubject. Upon the whole, the principles of M. Sage appear under the pen of our Author to more. advantage than they do in his own writings; they are unfolded with more perfpicuity and extent, and affume the air of a fyftem: the phosphoric acid acts here a capital part; it forms the bafis of metals, precious ftones, the fluor fpars, and is the principle of vitrification, according to Meffrs. Sage and Demefte. It cannot be denied that certain appearances favour thefe opinions, fuch as the zinc's yielding a flame, the diamond's exhibiting a flame alfo when exposed to a hot fire, the fufible fpath's yielding a phofphoric flame, when thrown upon burning coals, and the fixed alkali's producing glafs with quartz: nevertheless the doctrine of these ingenious men will require farther proofs and experiments, in order to its complete eftablishment on the ruins of former opinions. The fecond volume of this work, in which nature is to be confidered in her different afpects, mineral, vegetable, and animal, is in the prefs, and a speedy publication is announced. ART. VIII. Penfieri intorno a vari Soggetti di Medicina Fifica e Chirurgica, &c.— Thoughts concerning different Subjects of a Medical Kind, that have a more immediate Connection with Chirurgery and Natural · Philofophy, in Three Differtations, by DR. FRANCIS BERLING HIERI, Profeffor of Medicine, &c. in the University of Pifa. 8vo. Lucca. 1778. I T often happens, that after a laborious application to the study of the theory of medicine, a fagacious and learned phyfician is at a lofs in regard to the ufe and application of those remedies, whose effects are the most fully afcertained, and which are the Nn 2 moft moft frequently employed in the art of healing. This uncertainty is partly owing to the ftill prevailing ignorance of several of the most minute and effential parts of the animal economy, and which has engaged our Author to confider (in the first of thefe differtations) the obftacles to the improvement and progress of the practice of phyfic, that arife from the mechanism of the human body, and the erroneous methods of studying it. In treating this delicate and difficult fubject, DR. BERLINGHIERI fteers with fagacity and judgment between the credulity of the medical bigot, and the folly and impertinence of the medical fceptic. He acknowledges his ignorance, and that of his brethren, with respect to many objects, in which the poor patient believes them enlightened, and trufts in them with an implicit faith, and a foolish face of admiration and confidence; and he is not ashamed to advance the following propofition, fo humiliating to the fons of Efculapius, that the numerous and ftriking discoveries in anatomy, fo much celebrated in the last and prefent centuries, have not, as yet, contributed in the leaft to the progrefs and improvement of medical practice. He unveils, in a great many respects, the defects of medical fcience; and, though he may do real fervice to truth by this modefty and candour, he takes away much illufory comfort (ftill it is comfort) from the fick, who look up to their medical Popes, as clothed with infallibility, and cooperate fuccessfully with them in the cure, by the effects of this confidence. He obferves particularly, that the indications derived from the fenfible qualities of the blood and the motions of the pulse, are by no means fure guides, either with respect to the knowledge of the nature or caufes of difeafes. And after many reflections of this kind, relative to the theory and practice of phyfic, he proposes some attempts to correct the noxious qualities of the air in unhealthy places, and more especially in that district of Tuscany which is known under the denomination of Maremmes; and concludes his differtation by a judicious plan for directing the ftudies of the medical youth in the hospitals. The fecond Differtation is thus entitled: Concerning the natural and morbific Fire of the buman Body, and certain Difeafes which are produced by it. DR. BERLINGHIERI demonftrates, or, at least, proves, that in the human body, while alive, there is an inflammation of a peculiar character, which, when it does not exceed a certain degree, nourishes life and health,-that this inflammation, and the heat that refults from it, are not produced by the friction which the fluids meet with in paffing through their tubes-that this inflammation augments confiderably in those parts where the tumour (called inflammatory) is engendered-that this inflammatory tumour can only form itfelf in the nervous parts, and confequently has never its feat in the membrana adipofa, or cellular fubftance, which is, on the contrary, very fre quently quently the place where cold tumours are found. Our Author defcribes with precifion and perfpicuity the manner in which the inflammatory tumour is formed and increased, proves that the nerves have another property not lefs effential and diftinctive than their fenfibility, and lays down a theory for the cure of this diforder, which he confirms by experimental proofs of the falutary effects of his medical precepts.-This is followed by a curious difcuffion concerning fuppuration, and pus, in which the Author unfolds points of view, that may be useful in practice, and that are new to us. He diftinguishes pus into two kinds, the one corrofive, and the other he is inclined to call nutritive. This laft is produced from the nutritive part of the ferum, which divides and precipitates itself like a sediment, when it is in a state of ftagnation, and begins to be loaded with a collection of putrid matter.-One of the good confequences of this difquifition is, that it will fometimes prevent our being alarmed, when we fee a confiderable quantity of pus or purulent matter iffuing from the lungs, the uterus, the vagina, the ureters, fince this may happen, fays our Author, without any confiderable damage, nay fometimes without any damage at all, to thefe parts. An irritation of the nervés, a weakness in the membranous fubftance of thefe parts, is fufficient to occafion a feparation of the serous viscous humour that is defigned to consolidate their furface, and from thence refults the evacuation of pus here mentioned. The method of curing this indifpofition furnishes our Author with an occafion of communicating feveral useful obfervations. The third Differtation (the fubject of which is the Dropfy) contains a method of curing that diforder, when lodged in the peritonæum by a chirurgical operation, which is attended with no difficulty and little danger. This operation confists in an incifion of three or four fingers breadth made in the membrane which contains the vitiated matter; and this incision must be kept open during the whole time of the cure, both that the entire evacuation of the matter may not be prevented, and that the membrane may be cleanfed by proper injections. The falutary effects of this method of cure are abundantly afcertained by unanswerable arguments, that is, by facts. Of twenty-eight perfons, fays he, who underwent the paracentefis, or tapping, for a dropfy in the peritonæum, not one escaped; whereas of eight, who fubmitted to the operation already mentioned, only two died, on whom it had not been made with the proper precau tions. The remaining parts of this differtation exhibit to us reflections on the incifions that may be made in the breast for the cure of pectoral dropfies,-on the paracentefis in the pericardium, when the dropfical complaint attacks that part,-on the incifions Nn 3 that |