amm, terræ fol. tart. pil. ruffi ai dr. j. balsam. Peruv. q.f. f. pil. gr. iv. three every three hours. Thus he was perfectly cured. This chapter contains feveral other cafes of inferior importance.

In the next chapter, which is the eighth, the Author confiders the colica pictonum pathologically. Obferving that out of the nine cafes related in the preceeding chapter, in no les than feven, lead was the caufe, he accounts for the frequency, of this diforder from the number of people employed in lead mines, the many artificers and apothecaries who ufe this metal, its being fo frequently employed in the adulteration of wine, and as a remedy in many difeafes. The nature of the proximate caufe, he obferves, renders our prognofis uncertain, it being impoffible to determine, whether the difeafed ftate of the inteftines be fuch as to admit of a remedy. The fymptoms are variable, not critical, and frequently inexplicable. As to the method of cure, the Doctor is firmly of opinion, that after the exhibition of opium and cathartics, oily medicines are chiefly to be depended on; and with regard to the palfy, as a symptom or confequence of this disease, he depends principally upon electricity.

In the ninth chapter we have the hiftory of a compleat tetanus, the confequence of the colica faturnina. The patient died on the twentieth day of the disease.

Chap. X. is a differtation on the tetanus, its fpecies, and method of cure, as practifed from the earlieft ages to the prefent time. Having enumerated the principal Authors who have written on this diforder, the Doctor proceeds to confider its fpecies, caufes, prognosis, cure, &c. and fubjoins several histories of cafes which have fallen within his own observation.

Chap. XI. treats of the miliary and petechial fever. This chapter is chiefly employed in replying to Dr. Pringle's answer fubjoined to his Obfervations on the Difeafes of the Army. Such of our Readers as are defirous of entring into the merits of this difpute, we muft refer to the book itfelf, as it would be impoffible to do juftice to the Author before us without tranfcribing the whole. It is fufficient to obferve that he continues firm in his opinion that miliary and petechial eruptions in acute difeafes, are generally the effect of improper treatment, and never critical.

Chap. XII. contains obfervations on various fubjects. In the firft fection, the Doctor gives a fuccinct account of the Authors who have lately written on the virtues of the uva urfi. He informs us likewife that he has received feveral letters from different parts of the world, fome of which mention this medicine having been tried without any effect; others on the contrary confirm its lithontriptic power. Sect. 2. mentions a number of new experiments made with great accuracy by Van Doeveren, which entirely everturn the pr.fent fyftem of the irritability and L12 fent.bil

fenfibility of different parts of animal bodies. Sect. 3. confirms, from repeated experiments, what the Doctor had formerly advanced concerning the virtues of the liquor of the liver of the muflela fluviatilis, as a collyrium in removing fpecks on the eye. In fect. 4. the Author proves, from many years experience, that the fuppofed emetic quality of Kermes mineral, and flibium diaphoreticum non ablutum, when adminiftered with acids, or when there is an acid in the ftomach, is without foundation. In fect. 5. The Doctor recommends cold water as an efficacious remedy in hæmorrhages of the lungs or stomach. Sect. 6. informs us that, for want of a fufficient quantity of vipers, the Doctor had not been able to make fo many experiments as he intended, in order to afcertain the medical virtues of those animals in obftinate cutaneous disorders, and extream debility. He promifes however to procure a fufficient quantity from Italy against next year. Before we hear the refult of his intended experiments, we will venture to prophefy, that, in extream debility, he will find them equally nutrimental with many other species of food, and, in cutaneous diforders, of no effect at all. Sect. 7. treats of inoculation as an uncertain and dangerous practice. How well foever this opinion may be received in other countries, where they have had lefs experience of this falutary invention, yet, in this nation, where it has been attended with fuck amazing fuccefs, it will gain the Author very little credit. Nevertheless, the medical world is greatly obliged to the Author for the publication of his Ratio Medendi, every number of which contains many important obfervations, and useful experiments.

Dictionnaire de Chymie, contenant la Theorie & la Pratique de cette Science, fon application a la Phyfique, a l' Hifloire Naturelle, a la Medicine, a l'Economie Animale, &c. 8vo. 2 Tom. Paris, 1766.

A Dictionary of Chemistry, containing the Theory and Practice of that Science, its Application to Philofophy, Natural Hiftory, Medicine, and the Animal Oeconomy; together with a circumftantial Explication of the Virtues and Operation of Chemical Medicines, and the fundamental Principles of the Arts, Manufactures, and Trades, which depend on Chemistry. 2 vol. Paris. Lacombe.

TH

HIS dictionary is generally fuppofed to be the work of the celebrated chemist Macquer; but if it be really fo, we acknowledge ourfelves at a lofs to conceive, why an author whofe other chemical productions have been fo well received by

the

the public, fhould have with-held his name from the title of this.

The alphabetical method of arrangement is of all others the leaft fyftematical, and confequently the leaft proper for the study of a young chemift: nevertheless, it may be useful to those, who being already acquainted with chemistry, may have occafion to confule particular articles, which in a dictionary are more readily found than in a fyftematic work.

It being impoffible to give an adequate idea of the contents of a performance of this nature, we fhall only tranflate a fingle articic, as a fpecimen of the author's manner:

AFFINITY. We are to understand by the word affinity, the tendency of the parts, whether conflituent or integrant, of bodes, one towards another, and the power which causes their cohenon when united. Hence it appears that the word affinity is not to be numbered among thofe vague terms which convey no ides. The power by which bodies tend to unite with each other, and their mutual adhefion, are fenfible and palpable effects because that power cannot be deftroyed but by a power as real and more confiderable. This is demonftrable by an infinity of experiments, as for example, by the cohesion of two bodies whole furfaces are well polifhed; the mutual tendency of two drops of water, which being brought into contact instantly mix and form one mafs; the convex or fpherical figures affumed by the drops of different fluids, when fingle, or united to a body with which they are not difpofed to unite: effects which take place even in vacuo, and which demonftrate the affinity of integrant parts of bodies as well folid as fluid.

The affinity of the conftituent parts of bodies is demonstrated by every phænomenon in chemistry.

It is not our bufinefs, in this place, to enquire into the caufe of this great effect, which is fo general, that it may be confidered as the caufe of all combinations. It is perhaps a property as effential to matter as extenfion and impenetrability, and concerning which we can fay no more than that it is fo. On this fubject may be confulted the works of Newton, Friend, Keil, and Marcuzzi, who have attempted to throw the light of calculation upon this dark fubject. We fhall content ourselves with pointing out the principal laws obferved by the conftituent partsof bodies in their different unions and combinations in virtue of this property. Mr. Macquer diftinguishes feveral species of affi-. nities. Not that he imagines them effentially different; it being very certain, that it is always one and the fame property of matter differently modified in different circumftances. Intention of that writer is only to diftinguifh the various phanomena produced by this property in the combinations and fe

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parations

parations which take place in the moft general operations of chemistry.

He calls fimple affinity, the difpofition of the integrant and homogeneous parts of the fame body, to unite and adhere together, or the different parts of two heterogeneous bodies; which divides it into two fpecies.

The firft fpecies of fimple affinity produces only the union of aggregation; that is, the refult is a body of the fame nature, but of a larger mafs; this M. Macquer calls affinity of aggregation: as for inftance, when feveral particles, being feparated from a piece of earth or metal, are again united by fufion into one mafs.

The fecond fpecies of fimple affinity produces the union and cohesion of heterogeneous parts, forming a new body with properties different from either of the principles of which it is formed this is called affinity of compofition, because the result is really a new compound body. If, for example, the integrant particles of the vitriolic acid be united to thofe of iron, a third body is produced, which is called vitriol.

Concerning thefe fimple affinities we are to obferve,

ift. That the affinity of aggregation oppofes that of compofition; for it is evident that the power which caufes the cobefion of homogeneous and integrant parts of a body, prevents their difuniting in order to be joined to another body.

2d. It follows, that by deftroying or diminishing the cohefion of aggregation, you facilitate the affinity of compofition.

3d. The hardnefs of a fimple and homogeneous body depends entirely on the cohefion of aggregation between its integrant parts. If we deftroy this cohefion by feparating these parts, that is, by reducing them to powder, or, yet more compleatly, by the interpofition of a fluid to which they either do not adhere at all, or lefs than to each other; thefe parts, thus feparated, will more readily unite with thofe of another body, being more distant from each other by means of this mechanical divifion.

4. Different bodies being more or lefs fufceptible of this divifion, muft neceffarily form combinations with other bodies with greater or lefs facility.

5. But the facility with which one body unites with another, by an affinity of compofition, does not alone determine the degree of affinity which it bears to that body: for we find, by experience, that the conftituent parts of certain compounds, which unite with great facility, cohere nevertheless fo weakly, as to be decompofed by the leaft effort of chemical analyfis; whilft on the contrary, other bodies which cannot be united

but

but with difficulty, and by extraordinary means, unite more intimately, and are with greater difficulty decomposed. Mercury, for instance, unites more readily with the nitrous than the marine acid, nevertheless it adheres more obftinately to the latter.

Hence we may conclude, that we are not abfolutely to determine, that one body has no affinity with the other, because we are not acquainted with any means of uniting them. On the contrary, it seems certain that all bodies in nature have with each other a certain degree of affinity, a facility of uniting, a certain degree of cohefion when united, and confequent); that there are no combinations which are abfolutely impoffible; but that this degree of affinity differs, according to the different ftates in which bodies are found.

But fince the defect of union between two bodies really prevents their affinity from being manifeft, till chemistry is fo far advanced as to produce combinations which feem at prefent impoffible, we may continue to regard thofe bodies which refufe ,to unite as having no affinity with each other. Thus, for example, we fay that oil has no affinity with water, lead with iron, iron with mercury, because in fact, those bodies do not unite directly; fo that the affinity which they may have with each other is ineffectual with regard to us. On the other hand, as the affinities of bodies which unite produce in the operations of chemistry effects proportioned to the facility of uniting, and the force of their adhefion, we may confider the affinities of bodies in general, as being in a compound ratio of these two properties, &c.

Compound affinity is that in which there are more than two bodies acting upon each other. We are first to confider that in which only three principles are concerned. Two of thefe being united, if a third is prefented there will appear phenomena of compofition or decompofition differing according to the affinities which the three bodies have to each other.

1. Sometimes the third principle, uniting with the other two, forms a compound of three principles. For inftance, it to a mafs compofed of gold and filver a portion of copper be added, this third metal unites with the other two, and there, refults a compound of three principles: this happens when the third principle has an equal, or nearly equal, affinity with the two others as they have with each other.

2. The fame thing may alfo happen, though the third principle has no affinity with one of the two already united. But then it is neceffary that the third principle fhould have the fame affinity with one of the two, as they have with each other. In this cafe, that of the two principles which acts as the bond of union between those which have no affinity, is called interme diate. This therefore may be called intermediate affinity. If LI 4

f.