origin from the matter of light? This appears to be the cafe, when the eyes of a paffionate man inflamed by anger, or by love, feem to be on fire; or when the eyes ftrike fire, in confequence of a violent blow.'-This is one of the many fpecimens that occur in this treatise, of the lax mode of philosophifing adopted by the Author; and which, not long fince, we took occafion to expofe, when we had the work of a preceding, - otherwife refpectable, theorist (M. Buffon) under confideration *. Were this mode univerfally adopted, the lights which we owe to the Experimentalifts of this and the laft age would foon be obfcured; and the philofophical world would again be involved in all the wordy darkness of the Peripatetics. Thus, among the proofs which the Author adduces, to fhew the great difference, and even contrariety, between the nature of light and that of fire; he urges, that Light not only enjoys an illuminating property, without producing any change whatever in the parts of the illuminated body; but likewife, a cherishing or refreshing (refocillante effectu) and, as it were, revivifying quality: that is, a property nearly contrary to that of heat, and fire; by which, according to their different degrees, bodies are not only more or less changed, but are often destroyed.' According to the Author's fyftem, no heat, or fire, exifts in the folar rays. Some of his reafons for maintaining this propofition are becaufe, when the Almighty faid, "Let there be light, &c." fire could not then exift: for at that time, no bodies had been created on which it could act. To render the folar rays capable of producing the fame effects on bodies, as are produced by fire, it is requifite that there fhould be a folid inflammable matter, on which they might exert their action; for the fun's rays produce heat folely by their action upon bodies. But pafling over the Author's mode of reasoning on this fubject, we need only observe, that this propofition is equally true with refpect to culinary fire, when exhibited in the form of luminous rays; particularly when the burning and luminous body is placed, for inftance, in the focus of an elliptic fpeculum. No fire, the Author continues to fay, exifts in the folar rays; for Boerhaave found that, even when collected into a focus, they would not produce any detonation with nitre. But furely the learned Author cannot be ignorant, that neither the rays of common fire, nor even an ignited body in contact with nitre, will produce any fuch detonation, without the prefence of phlogifton, or of an inflammable fubftance. If he means only to prove, that there is no phlogiston in the folar rays; he is con * See Appendix to our 51ft volume, pag. 519. tending tending for a propofition that no one, we apprehend, will oppofe: bat that this is not his intention, is pretty evident from many of his arguments; fuch as the diminution of the folar heat at the tops of mountains; its not bearing a conftant relation to the latitudes of places, or to the greater or lefs obliquity of the folar rays; and other matters totally unconnected with this particular circumftance. Some of the remaining proofs of the difference between solar and common fire are-that the folar rays, in themselves, are certainly of the fame quality in vacuo, as in the air; but that though, when collected into a focus, they will fire gunpowder in the air, they will only caufe it to melt and fume in vacuo. They have therefore, argues the Author, no heat, but that which they acquire from the air, or from certain fubftances floating in it.-But is it not true likewife, that common fire applied to gunpowder, will produce the fame effects, under the fame circumftances?That the folar rays, how much foever concentrated, will not produce fire, without the acceffion of a combustible matter;-but will common fire act without fuch an acceffion? That the folar rays have for many ages acted, and continue to act, without any diminution, and without any pabulum, or smoke: whereas, common fire is continually on the decline, requires a renovation of the pabulum, and is attended with effluvia. But if,' fays the Author, the fun be an ignited body, who fet fire to this immenfe mafs of matter? How could the whole of it, altogether, and at once, burst into flame? Matters expofed to the action of common fire are only kindled fucceffively. Who will dare to fay, that God fift created this immenfe globe, and then fet it on fire; which must be the commencement of its deftruction? To fuch abfurdities muft those be reduced, who confider the fun as being an ignited body.'-The abfurdities, however, depend only on the manner in which the Author chufes to frate the circumftances. From the confideration of fire, the Author proceeds to that of water. Thales himself fearce afcribed greater univerfality to that element. He contends that, at the time of the creation, the whole of the air that furrounds this globe was produced from water; and that earth likewife owes its origin to the trans mutation of water into that fubftance. He affirms, that water, while boiling on the fire, and as long as a drop of it remains, is converted not only into a denfe vapour, which returns to the ftate of water again, but into a ftill rarer vapour likewife, which is real or permanent air; but we do not here meet with a fingle proof of this ftrange propofition. From the confideration of common air, the Author is led to treat of fixed air. He proposes the queftion, whether, in the proceffes for obtaining it, it fhould be confidered as eductum, vel productum; productum; that is, whether it previously exifts in the fubftances from which it is obtained, on the addition of acid liquors; or whether it is only an extemporaneous modification of these acids. He determines in favour of the latter opinion; but founds his determination on fuch grounds, as fhew him to be very little converfant, or at leaft very ill informed, with refpec to the prefent ftate of this particular branch of knowledge. To go even fo far back as Dr. Black's difcoveries, with refpect to the fixed air contained in lime-ftone ;-the Author obferves, that Dr. Black's hypothefis on this fubject was attacked, and that of Meyer was defended, by M. Crantz: and he expreffes his furprife, that none of the patrons of fixed air, have hitherto (to his knowledge) attempted to defend Dr. Black's theory, as far as they had it in their power.-Paffing over Dr. Black's powerful German fecond, M. Jacquin, who, in 1769, verified his experiments, and confirmed his theory by new ones; we need only to name M. Lavoifier, who, not very long afterward, fully eftablifhed the credit both of the experiments and the theory, with a measure and a balance in his hand. To these two philofophers alone we may fafely refer the learned Author, for an answer to the various objections which he hereproposes against this new theory of fixed air.'-We fhall only take notice of two of them. When artificial nitre is made, by adding fpirit of nitre to a fixed alcaline falt; the fixed air fuppofed to refide in the latter, is faid to be all expelled by the acid: but if this were really the cafe, how happens it, fays the Author, that when the nitrous acid has been expelled from the alcali, in the fubsequent deflagration of the nitre with charcoal; and fresh fpirit of nitre is then added to the alcali deferted by it; as great an effervescence, and as large a quantity of fixed air prefents itself as at firft? Whence does this fresh ftock of fixed air proceed? It proceeds, we will inform the Author, from the particular inflammable fubftance employed to expel the nitrous acid; whofe place one of its principles immediately occupies at the very inftant of the deflagration. This, however, only happens when the inflammable matter employed in the procefs contains fixed air as is the cafe when charcoal is ufed. In the deflagration, the alcali receives its fixed air, or mephitic acid from the charcoal; in the very fame manner as it receives the vitriolic acid, when fulphur is employed in the deflagration. The Author must be too good a chemist not to know, that when filings of iron, zinc, &c. which contain no fixed air, are used in this procefs; the alcali left after the deflagration will not exhibit any appearance of fixed air, on the addition of fpirit of nitre. This matter is fully explained towards the end of Dr. Prieftley's Experiments and Obfervations, &c. Vol. III. p. 386. After After denying the exiftence of fixed air in lime-ftone, the Author endeavours to reduce the patrons of fixed air to a dilemma, by the following reafoning. It is alleged by them, that lime owes its folubility in water, to the expulfion of its fixed air, by calcination: but magnefia, treated in the fame manner, is infoluble in water. He wishes to be informed, how effects thus contrary to each other, can be produced by one and the fame caufe. But furely the inference implied in this queftion is highly illogical. Can any thing be more natural, than that one and the fame fubftance may, by its prefence, or absence, produce or occafion different effects in different bodies; or even in the very fame body, when the circumítances only are different? The Author next undertakes to prove, beyond any poffibility of doubt,' that all the earth of the prefent terraqueous globe was derived from water, as well as that which conftitutes the bafis of vegetables and of animal bodies; and for this end, he endeavours to ascertain not only the poffible, but the actual transmutation of water into earth, in various inftances. He not only relates the many well known experiments, in which this tranfmutation appears to have been actually effected; but offers likewife various other obfervations tending to prove the poffibility of this converfion; which, however, are not of fuch a nature as to fatisfy even the leaft fcrupulous philofopher. It is far from our intention to treat a writer of such acknowledged merit as our Author with difrefpect; but we muft obferve that, in numerous instances, which occur in this work, he is not very nice in his proofs; but employs any one that seems to serve the prefent purpose, indifcriminately;-whether ftrong or weak, and whether drawn from philofophy or fcripture: for to this laft the Author chufes likewife to appeal, even on philosophical questions. According to the Author, water is converted into earth, in the various proceffes of vegetation, animalifatión, agitation, trituration in glass mortars*, putrefaction, coagulation, by means of the fparry acid difcovered by M. Scheele, and diftillation. With refpect to the results attending this laft procefs, our philofophical readers may confult the particular account we gave of M. The Author affirms that by a long continued trituration of diftilled water, without intermiffion, in a glafs mortar, he first prodaced veficles; that afterwards the water became lefs fluid, and appeared, as it were, coagulated; and that at laft it was changed into a light white earth, adhering to the bottom and fides of the mortar. From only one drachm of water he declares that he obtained about one fcrupule of this white earth; which he affirms to have found, On examination, to be of a different nature from that which can be obtained from glass. Lavoifier's Lavoifier's experiments; [See Monthly Review, vol. L. Appendix, June, 1774. P. 544.] or Dr. Priestley's account of his trials made on water fubjected to a very ftrong and long continued heat, in tubes hermetically fealed; and which are contained in his late volume of Experiments and Obfervations, &c. M. Lavoifier afcribes the earth which he procured by the diftillation, or rather cohobation, of the pureft diftilled water, to the abrafion of the particles of the glafs veffel containing it: as he found that the pelican which he employed had loft about as much of its weight, as was equal to that of the earth procured. The Author controverts this conclufion. He first questions the accuracy of the balance employed in this experiment. He does not think that M. Lavoisier ufed a fufficient degree of beat: [This objection, however, does not militate against the trials made by Dr. Priestley; who is inclined to fufpect that his proceffes were not continued a fufficient length of time] but bis principal objection to M. Lavoifier's conclufion is, that the lofs of weight obferved in the pelican, at the end of the experiment, might, with equal probability, be afcribed to the action of the fire on its external furface, as to that of the water on its inner furface properly obferving, however, that a chemical examination of the earth procured in the procefs, and a comparison of it with the fubtle powder of glafs, would beft fettle this point. Having fhewn that both air and earth owe their origin to water, he confiders all natural bodies as confisting only of three principles; the inflammable, the faline, and water: and then refolving the faline principle into the aqueous and the inflammable, he concludes, that the principles of all natural bodies are neither more or less than two;-earth- which is undoubtedly the principle fo called by Mofes,' [Gen. i. ver. 1.] and the matter of light, pure fire, celeftial fire, and which is denominated calum by Mofes," The Author endeavours to fhew, how the various bodies in nature may be formed out of thefe two principles, in confequence of their different modifications, or the varieties introduced by figure, greater or lefs cohefion, &c.: but he labours ftill more ftrenuously to fhew, that his fyftem has the countenance of Mofes, in his hiftory of the creation; where he fuppofes him not to have given a partial hiftory of the creation of this earth, but of the whole vifible univerfe. The pious Author accordingly expreffes the utmoft anxiety, left his philofophical and chemical principles, or his deductions from them, fhould be found contrary to those of the facred hiftorian, and- Maximum phyficum, Mofen;'-who, we acknowledge, was undoubtedly fkilled in all the learning of the Egyptians-but how far that learning extended, with refpect to the philofophical part of the prefent inquiry, we can not, |