sufficient, alone, to affign the place, which human nature ought to hold in this grand scale."

The thirteenth book treats of the researches and observations relative to the planets and the progress of astronomy, since the discoveries of Newton, or from the year 1687 to 1730. The fourteenth contains researches relative to comets and stars, and the progress of astronomy during the period last mentioned.

This volume is terminated by M. BAILLY's discourse concerning the nature of luminous and obfcure bodies in the universe, and a vocabulary designed to explain certain astronomical terms, which may escape the knowledge of numbers, whom the beauty, perfpicuity, science and amenity, that jointly adorn this excellent work, will engage to peruse it.

ART. VII.

Lettres du Docteur DEMESTE, Correspondant de la Societé Royale de la Medicine, au Docteur Bernard, &c. Sur la Chymie, &c. - Letters concerning Chymistry, Christallography, Decimasticks*, Lithology, Mineralogy, and Natural Philosophy in general, addressed to Doctor BERNARD, first Professor of Physic at Douay, and Fellow of the Royal Society of London, by Dr. DEMESTE, Correspondent of the Royal Society of Medicine, &c. with this Inscription : Novus rerum nascitur ordo, Vol. I. Paris. 1779.

T

HESE letters are

the production of a

masterly writer,

and an accurate observer.-Perfpicuity and precision, method and order, diftinguish the manner in which the Author expresses his ideas; but his discussions, like many others of modern times, shew us, that physical theories are as little afcertained, and are not a whit more susceptible of evidence in the analytic line, than metaphysical ones.

The title shews the kind of entertainment, which the philosophical, and more especially the chymical Reader, is to expect in these letters. The first discussion we meet with turns upon elementary substances, among which some will be surprised to find, neither fire, nor air, as our Author adopts the hypothesis of Sage, confiders these as mixed bodies, of which the former (composed of phlogiston and elementary acid) contributes to the formation of the latter, by a combination with the aqueous principle. You see, gentle Reader, how far the air is from being an element, or simple principle, upon this hypothefis; it is so far from being fimple, that it is a double-compound. This notion is illustrated and confirmed with great fagacity and depth of reasoning in three of the letters that compose this volume, to which we refer the curious Reader.

These elements, which we still look upon as dusky beings after all these illustrations, lead our Author to treat of affinities,

* A new French term for experimental chymistry, and more especially mineralogical experiments.

another phenomenon, that has been sometimes gently bending the tongues and pens of our physical theorists towards the profound language, that procured veneration to occult causes some centuries ago. It is the doctrine of M. de Buffon, whose genius is of the comprehenfive and combining kind, that the laws of affinities are the fame with that general law by which the cеlestial bodies act upon each other, and that they (affinities) exert their powers in the same proportions of masses and distances. Sage, in the year 1773, composed a table of affinities upon this principle of gravity; but a farther observation of M. de Buffon, if it be true, renders this principle inadequate to the phenomena, and consequently uncertain and ambiguous: the observation is, that figure, which in the celestial 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 extensive influence, and does almost all, in the affinities between bodies, whose distance from each other is small or null. Now this observation disconcerts the hypothefis of specific gravity; for if the degrees of affinities depend absolutely upon the figure of the constituent parts of bodies, these degrees muft, like the figures, vary ad infinitum, even where the specific gravities are the fame. The different operations of different falts on various substances, and the different crystallizations, that are obvious to the eye of an attentive observer, will not permit our Author to call in question this observation of M. de Buffon. He affirms, nevertheless, that our perfect ignorance of the figure of the constituent parts of bodies, which the philosopher of Paris has been so gracious as to acknowledge, obliges us, in our enquiries after the causes of particular affinities, to confine our researches to the different proportions and relations which take place between the specific gravities of the particular substances. That is to say-we do not know the true cause, and therefore must take up with such a cause as we can come

at.

Simple affinity is the tendency of two homogeneous bodies to mutual union and cohesion, 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 substances, unless a third substance 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 substances, that do not appear to us at all homogeneous, blended together, with ease, in the most perfect union; but, on close inquiry, it will be found, adds he, that these substances 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 diffolvents

APP. Rev. Vol. lx.

Nn

diffolvents and chymical menftruums, which act palpably on substances with which they seem to have no analogy; but no menstruum, 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 metallism (if we may use that term), contains an acid.

The relation, then, of analogy or homogeneity, that different substances have with their menstruums, and these latter with their substances, is what the Chymists more especially distinguish by the name of affinity, and the different degrees of this relation seem 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, 1st, the relation or analogy of different menstruums to the same substance; 2dly, the relation of different substances to the same menstruum. 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 substances, which are known, at present, under the denomination of gas. We find under this article, the relation of a fact, which proves, in a very striking manner, the anti-septic quality of fixed air or the mephitic acid. At Latera (fays our Author), near Bolfena in Italy, a goat which had died in the vapour of a non-inflammable moffet, was observed 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 saline substances, with his usual sagacity; and then proceeds to lithology, or the history of stones. Linnæus was the first who perceived that there can be no crystallization without a faline principle, and therefore ranged cryftallized ftones in the class of falts. Sage generalized still farther the idea of Linnæus, and being convinced by the analytic process, that all the earths and stones of which our globe is compofed, result from a combination of one or more acids with an alkaline or terreous basis, he concluded from thence that they must be real, faline mixts, though void of tafte and favour, and almost all indissolvable in water *. M. Romé de L'Ifle, by his crystallographical observations, has also confirmed this hypothefis, and shewn the analogy there is between salts and stones. Our Author adopts the division, made by M. Sage, of lithology into fix classes, but

* Our Author fays almost all, -for the gypsum or plaster stone, of which there are such immenfe quarries, is really, notwithstanding the general opinion, susceptible of solution in a large quantity of does not arrange stony substances in these classes in the fame manner with that famous mineralogist. He describes with the greatest accuracy all the crystals 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'Isle's excellent effay (as it is modestly called) concerning crystallography. These 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 crystallogical researches will appear greater than may be imagined at first fight, when it is confidered, that they furnish consequences and refults, which explain the formation of those rocks of the granit kind, which the most celebrated naturalifts, at present, consider as a mass that sustains 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 system: the phosphoric acid acts here a capital part; it forms the basis of metals, precious stones, the fluor spars, and is the principle of vitrification, according to Meffrs. Sage and Demeste. It cannot be denied that certain appearances favour these opinions, such as the zinc's yielding a flame, the diamond's exhibiting a flame also when exposed to a hot fire, the fusible spath's yielding a phosphoric flame, when thrown upon burning coals, and the fixed alkali's producing glass with quartz: nevertheless the doctrine of these ingenious men will require farther proofs and experiments, in order to its complete establishment on the ruins of former opinions.

The second volume of this work, in which nature is to be confidered in her different aspects, mineral, vegetable, and animal, is in the press, and a speedy publication is announced.

ART. VIII.

Penfieri intorno a vari Soggetti di Medicina Fifica e Chirurgica, Sr.Thoughts concerning different Subjects of a Medical Kind, that have a more immediate Connection with Chirurgery and Natural Philofophy, in Three Dissertations, by DR. FRANCIS BERLINGHIERI, Professor of Medicine, &c. in the University of Pisa. 8vo. Lucca. 1778.

T often happens, that after a laborious application to the study of the theory of medicine, a sagacious and learned physician is at a loss in regard to the use and application of those remedies, whose effects are the most fully ascertained, and which are the

Nn2

:

most frequently employed in the art of healing. This uncertainty is partly owing to the still prevailing ignorance of several of the most minute and essential parts of the animal economy, and which has engaged our Author to confider (in the first of these dissertations) the obstacles to the improvement and progress of the practice of physic, that arise from the mechanism of the human body, and the erroneous methods of studying it. In treating this delicate and difficult subject, DR. BERLINGHIERI steers with fagacity and judgment between the credulity of the medical bigot, and the folly and impertinence of the medical sceptic. 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 proposition, so humiliating to the sons of Efculapius, that the numerous and striking discoveries in anatomy, so much celebrated in the last and present centuries, have not, as yet, contributed in the least to the progress and improvement of medical practice. He unveils, in a great many respects, the defects of medical science; and, though he may do real fervice to truth by this modesty and candour, he takes away much illusory comfort (still it is comfort) from the fick, who look up to their medical Popes, as clothed with infallibility, and cooperate fuccefsfully with them in the cure, by the effects of this confidence. He observes particularly, that the indications derived from the sensible 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 causes of diseases. 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 dissertation by a judicious plan for directing the studies of the medical youth in the hospitals.

The second Differtation is thus entitled: Concerning the natural and morbific Fire of the human Body, and certain Diseases 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 passing 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 substance, which is, on the contrary, very frequently