A Philofophical Effay concerning Light. By Bryan Higgins, M. D. Vol. I. 6s. DodЛley. Had Dr. Higgins entitled this performance a Chemical, inftead of a Pbilofophical, Effay, the reader would have been better apprized of the nature of the inveftigation, contained in it. We have more than once obferved, that chemistry is but a part of natural philofophy, and that its principles are by no means thofe of phyfics in general. It is for want of attending to this neceffary diftinction that phyfiologifts, who are adepts only in chemistry, fall into the moft palpable mistakes, in treating of firft principles in philofophy, and aiming at a fatisfactory folution of the phænomena of Nature. Hence it is, that their experiments fo frequently confirm the obfervation of Lord Bacon; which Dr. Higgins hath, we think a little unfortunately, adopted as the motto to the prefent effay; "Vaga enim experientia, et fe tantum fequens, mera palpatio eft; et homines potius ftupefacit quam informat." And hence it is, that we find fo many Aupified admirers of as stupified experiment-mongers; to the difgrace of this fuperficially-philofophifing age. Dr. Higgins hath not informed us how many volumes his effay is to take up; but if the building be, in any wife, proportionate to the portal, it will extend to many; the prefent volume, confifting of 256 pages, having no lefs than 229 of them taken up with the introduction. This, therefore, becomes the capital object of our prefent attention. Dr. Higgins fets out very properly with a general expofition of his manner, and with laying down his definition of terms. By microfcopic obfervations, and in a variety of natural and artificial proceflès, particularly in those wherein folid bodies are greatly expanded by menftrua, fire, and other means; we learn that every perceptible portion of matter is divifible into parts exceedingly minute, and feverally invifible. "As all bodies are compofed of these, and all natural operations are confequently performed by them, it is highly incumbent on us to guard against falfe notions of them, and efpecially againit the confufion refulting from the mifapplication of infinite divifibility, which may well be affumed by mathematicians who treat of extenfion and magnitude, but ought to have no place in our ideas of the material parts of bodies; because we can have no diftinct notions of a body indefinitely fmall; and becaufe in physical enquiries, every divifion, minuteness, or condition of matter, which is not deducible from experience, or neceffary towards explaining the natural phænomena, is to be rejected. "Avoiding therefore every fpeculation concerning ideal divifions, I confider the fmallest parts, into which any mafs of matter is ever di-. vided in the proceffes of Nature or Arr, as the ultimate parts of that mass, and as finall bodies which are incapable of actual divifion or dig munition, "Thefe minute bodies are very aptly called atoms; and ufing the word atom in this fenfe, I exprefs by it no more nor lefs, than what really exists. "A body confifting of two coherent and heterogeneous atoms, I call a molecule, after the example of modern chemists; and fmall bodies, compofed of an unknown number of cohering atoms, are by common confent called particles. 66 By common obfervation and chemical analysis, we learn that there are many mafies of matter, which differ from each other in their appearances and properties, and by thefe differences are diftinguishable into feveral kinds. "The maffes or bodies which, in any known process, are separable into parts diffimilar in their properties, are called compound bodies: and thofe, whofe ultimate parts or atoms, whether cohering or diftant, are ever found to be feverally endued with the fame properties, we call bomogencal bodies. "By the word Element, I exprefs the whole natural quantity of any fort of Matter, whofe feveral parts poffefs the fame properties. "Attractive Matter, is that whofe atoms attract each other. "Repellent Matter, is that whofe atoms, repel reciprocally.. "The power which tends to draw together any two atoms, or any two bodies, each of which is homogeneal, is called a fimple power of Attraction; and the attraction is named Simple Attraction. "The attractions of compounded bodies are called Compound Attractions; and the powers which effect these compound attractions, are denominated Compounded Powers. "The Polarity of matter is the tendency of the atoms to attract each other more forcibly in one direction or axis of each atom, than in any other imaginable direction or axis thereof." Having thus ftated his terms, our author proceeds to diftinguish between the feveral kinds of matter, which he conceives to exift feparately and effentially diftinct from each other. "The most experienced philofophers acknowledge, that the action of light and groffer bodies on each other, varies with the kind of matter, as well as with the denfity of the several bodies: and the ensuing pages will flew it is as neceflary in optics as in chemistry, that we should diftinguish and afcertain the number of the elements. I do not intend, on this occafion, deeply to engage in an enquiry fo extentive, and which demands many new experiments: but with a view to the ufes which I intend to make of the knowledge already ac quired concerning the number of the elements, I offer the following obfervations. "By common experience, all men are affured that the matter which, in combination, renders bodies combuftible, differs in many properties from that of water, and that the matter which chiefly conflitutes the aerial atmosphere, differs in many respects from that of earthy bodies; and that each of thefe different kinds of matter poffeffes fome property peculiar to itself. "In the earliest ages, these four were adopted as elements by the moft obfervant men, who ufed the word fire to exprefs that part of compound combuftible bodies, which we call phlogifton: and the mo dera dern philofophers, who are beft acquainted with the compofition of bodies, are agreed in admitting an earthy, an aqueous, an aerial, and phlogistic element, on various confiderations; and especially for this reason, that feveral compound bodies may be refolved into portions confifting of earthy matter, or water, or air, or phlogiston; but these portions, however examined or divided into their ultimate parts, are found to confift of atoms fimilar to each other in every refpect. "In chemical analyfis we difcover two other portions of matter, called acid and alkali : and I do not hesitate to rank these in the number of elements; because the acid or alkaline matter, when feparated from bodies, forms an elastic invifible fluid, which, in all the experiments lately made, appears to admit of no decompofition, and to be truly homogeneal; and thefe fluids differ as much from each other, and from the elements already mentioned, as water differs from phlogifton. "The properties wherein all these differ from each other, need not be enumerated, because those which are known to all philosophers, are fufficient for our prefent purpose. "No one of thefe elements is to be rejected on the fuppofition that it is a compound formed of two or more of the others; because the several combinations of thofe elements conftitute known compounds: and because portions of any of thefe elements poffefs the properties peculiar to fuch elements refpectively, in a more eminent degree, in proportion as these portions are more accurately feparated from every other kind of matter. This appears by comparing the acid elastic fluids, with acid diluted in water, or combined with any known matter; in comparing the alkaline elastic fluid with mild alkali, or alkali diluted, or alkali faturated; in the comparison of moift or phlogistic air, with pure air; and in a variety of other comparisons which will readily occur to the experienced chemist. Light is a matter evidently different from the foregoing elements, and is to be added to the number of them; for it will hereafter appear, without any reference to what is faid in this place, that neither the prifmatic coloured fpectrum, nor any other phænomenon hitherto obferved, denotes light to be a fluid confifting of parts diffimilar in any respect. Thus we reckon feven elements of matter; namely, Earth, Water, Air, Acid, Alkali, Phlogiston, Light; the existence and differences whereof, will further appear as we advance in the enfuing enquiries concerning the reciprocal relations of the parts of matter. "Another, or perhaps many other elements, may be hereafter added to this lift: but in the prefent ftate of our knowledge, it feems more adviseable to reft on thefe only, than to reckon as many elements as there are portions of matter which have hitherto eluded the art of analylis, and which in vulgar operations feem to be homogeneal. This opinion is derived from the following confiderations. "Before the compofition of fulphur was difcovered, fulphur was confidered as an homogeneal body; and the philofophers who imbibed this notion of the chemists, were led thereby into many errors. "The native calcareous earths, gypfum, fluors, and other earthy bodies, were diftinguished as fo many homogeneal matles, until the modern chemists had discovered that they are compounds. "The "The elaftic inflammable fluid called inflammable air, was not reckoned amongst the compound bodies, until the laft winter, when we repeatedly compofed and decompofed it. "It was fufpected, many years fince, that the feveral acids of the chemiits, were compound bodies; but they were generally fpoken of as hombgencal bodies, until lately that we have found each of them to be compofed of acid matter afsociated with other kinds of matter. The like obfervations' may be made concerning the feveral alkalies of the chemifts, and various other bodies." "Thefe examples give us warning, that bodies are not to be held as homogeneal, merely becaufe we cannot yet feparate their heterogeneal parts; and ought to teach us, that all bodies which refemble each other in one or more of thofe properties, which characterize an element, ought to be confidered as compounds confifting chiefly of the matter of that element, and differing from it in fome particulars, by reafon of combination. And as all arkaline bodies are to be confidered as feveral portions of the alkaline element predominant in feveral compounds; and all acids bear the like relation to the acid element; and as phlogistic or impure air bears the like relation to pure air'; and as it is known that various liquors, whether fluid or congealed, bear the like relation to pure water or pure ice; and that all phlogiftic bodies have a fimilat relation to the phlogiftic element: we have no fatisfactory inftance of the existence of an element different from thofe we have enumerated, unless certain earthy bodies, or fire, or the electric fluid, be offered as " elements. As the number of earthy bodies formerly accounted homogeneal, has gradually decreased as chemical knowledge advanced; and as all earthy bodies agree in many common characters; we ought rather to examine what compofition or mode of aggregation conftitutes the difference between the feveral earthy bodies, than prefume that lime is an eement different from clay, and clay an element different from quartz, and quartz an element different from tale; or that the feveral metallic earthis are diftinct elements. "In treating of light, I fhall-endeavour to fhew that fire is not to be confidered as an homogeneal bedy different from light and phlogiston: and I am unwilling to admit the electrical fluid as an element different from thele, until I find that fuch an admiffion is neceflary towards our plaining the electrical phænomena. By thus diftinguishing and naming the elements, we fhall avoid confufion in fpeaking of the reciprocal relations and actions of the parts of matter: by admitting fewer elements than those which exift, our, Knowledge may be confined for a time, but it will be fubftantial: but if we had on the other hand miftaken compounds for elements, or af famed elements, which are not demonftrable; we muft neceffarily fall into the errors which ever flow from falle principles." Having given our readers a fpecimen of the manner in which Dr. Higgins propofes to profecute his fubject, we beg leave to defer the continuation of this article till next month; when we fhall do his mode of argument all poffible juftice, and yet fhew that he is very materially miftaken in his notions of light, A Thea A Theological Survey of the Human Understanding. Intended as an Antidote against modern Deifm. 8vo. 5s. Wallis. Continued from page 19, and concluded. The reader muft have already obferved, that our Theological Surveyor is rigidly orthodox in his divinity. It were to be wifhed, he were equally confiftent and well-grounded in his philofophy: but in this he appears to be very vifionary. Thus, however, it will ever be, when even the most ingenious men attempt to conciliate things, in their very effence, irreconcileable. The argument, of this author's pfychological Aricture before-mentioned, runs thus. "The doctrine of the refurrection of the body, being held in too grofs a fenfe by fome; whilft it is wholly difclaimed by others, who acknowledge, nevertheless, the immortality of the foul of man; it is, therefore, the intent chiefly, of this ftricture, (avoiding these two extremes) to evince, on the principles of reafon, that the fouls of the departed righteous, will be hereafter clothed with glorified bodies; rifing myfterioufly from the diffolution of their prefent mortal forms. and previous to this difquifition; the foul of man, in its abstract state, is fitly confidered." If our readers will not take the author's word for the latter affertion, they must have recourfe to the work itfelf; for as to the abftract fate of the foul of man, we do not think it here To give another fpecimen, a fit fubject of confideration. however, of our Surveyor's fingular, not to fay whimfical, ingenuity, we fhall cite his table of exiftence, or feale of being; which he introduces, in a digreffion, thus. Thus much for the prefent, concerning the foul of man: and, here, reader, I might intrude on thee, many wild conjectures concerning its effence; but as I know nothing of it, I fhall forbear; and inftead, entertain thee in the page following, with what I call, a Scale of Being; rifing from a mere fofil, to a weed; and thence through various ranks of creatures, gradually augmenting in animality and intellect, 'till we reach the throne of god himfelf: but the divine majef, I include not in it; because the chafm between finity and infinity, is too -Nor, indeed, do I pretend to great, for my invention to fill up.the greateft exactnefs, even in the fcale itfelf; it being a matter of Nor is it fo full as biftory, and, conjecture, rather than argument. it might have been. However, I have done my beft. In the Empyrean. | XXVII CHERUBIM or SERAPHIM, the living Throne of GOD: The conflant Attendants of the Divine Majefly:FOUR. Ijaiah vi. 2. Ezek. i. 5. and x. 5. 10. Rev. iv. 6. THRONES; FOUR and TWENTY. Rev. iv. 4. 26 25 ARCHANGELS, 24 ANGELS, f Dominations, THOUSANDS of THOUSANDS. |