On the whole, Mr. Pearfon has beftowed great pains on the performance, and we hope he will proceed with his work, and at the fame time make fuch additions to this first part as he may judge neceffary. As a text-book, it is rather too minute and particular; as an elementary book, not fufficiently explicit and fatiffactory to the reader.

ART. X. An Efay on the Powers and Mechanism of Nature; intended, by a deeper Analysis of Phyfical Principles, to extend, improve, and more firmly establish, the grand Superftructure of the Newtonian Syftem. By Robert Young. 8vo. 6s. Boards. Becket, &c. 1788.

BY

Y the Newtonian fyftem, Mr. Young means, the fyftem of the world, difcovered by Pythagoras, revived by Copernicus, and, by the aid of a fublime and exquifite geometry, brought to its prefent ftate of perfection by Sir Ifaac Newton;' and, after ftating that this fyftem is imperfect, in the preface,

he lays :

The following Effay is intended to improve the phyfical principles of philofophy, in order to extend our knowledge of nature. If I have fucceeded in thefe views, it will be no objection to my attempt, that I have deviated from principles already established, fince it is obvious, that every advance in knowledge implies the difcovery and renunciation of fome error; he who will adhere immutably to tenets once adopted, can never increase his light, nor improve his understanding.'

He then infifts on the neceffity of liberty in reafoning, inveighs against those who, in scientific matters, put implicit faith in human authority, and proceeds as follows:

Many will object to the method of reafoning herein followed, that philofophy has only to collect general laws from phenomena, and then apply thofe laws to the explanation of other phenomena; and has no concern with metaphyfics. To this I anfwer, that the prefent is a phyfical, and not a metaphyfical work (if metaphyfics are to be loaded with an unmerited opprobrium); that the object of my inquiry is not facts but powers, not effects but caufes; that the received theory doth not, agreeably to its profeffions, confine itfelf to the affertion of phenomena, but affumes, as caufes, phyfical principles, which are not matters of fact, nor laws collected by induction, but which are to be examined by phyfical reafoning alone. Thefe principles, thus affumed in the received theory, I have not adopted, and therefore it became neceffary to fubftitute others in their place, and to this end I have employed the following pages. I have not attempted it by means of experiments, because they can difcover effects only, and not caules which I fought; nor by geometry, because it is concerned only with relations of quantity, and cannot lead to the knowledge of being or of power.

by phyfical reafoning alone I have found a phyfical principle adequate to the purpofes of explaining phenomena; a fubftance ac

tually

tually exifting, poffeffed of active powers, the bafis of matter itself, and the agent in all effects. This active fubftance appears to have been the defideratum in all ages of philofophy; it removes the obfcurity which attends the confideration of matter as an original and inactive fubftance, whofe effence, folidity, is confeffed to be incomprehenfible; it removes the difficulty which has ever attended the queftion of the origin of motion, by fhewing motion to be the original form of being; and thus reflects a light upon the very foundations of fcience.' From these extracts, our readers may perceive what is Mr. Young's intention in the prefent work, and alfo the methods which he has used in 'executing it. We shall now briefly ftate the contents of the effay before us.

In the introduction, Mr. Young remarks, that philofophical principles are of two kinds, experimental and rational; the former are general facts, which are found uniformly to obtain; the latter are conceptions of the understanding, whofe evidence rests not alone on experiment, but on intuitive perceptions.' To arrive at thefe, he fays, we muft exercise our intellectual faculties.' He afferts alfo, that firft principles, not being objects of fenfe, are therefore not to be fought by experiment, but by reafon and intellect, and by analyzing those things wherein they exift.'

6

The first part of the prefent performance has the general title, Analyfis of Matter and Motion;' in which our author con fiders the qualities of bodies, and thence proceeds with his analyfis. The principal conclufions which he makes are, that folidity rofolves itielf into power or activity;' that inactivity is a privation, and incapable of analyfis;' that matter is both active and inactive in different refpects; its component parts are active, and, by their action, conftitute matter as an' whole inactive; that inactivity has no relation to motion, but is its negation; that the effence of body is power;' that cohesion is a power which, either in holding together any number of primary folid parts, or in conftituting one primary folid by holding its own parts together, is fimilar both in its nature and mode of operation;' that matter is not impenetrable.' In the chapter allotted to the Analysis of Motion, Mr. Young fays, 'We cannot conceive of any actual motion, without combining together these three ideas, a being which moves, a place in which that being is, and the change of that place.' After defining and explaining being, place, change, he concludes that all motion implies action, and depends on an active caufe.' He then confiders motion in its parts: every motion,' he lays, has a beginning, a middle, and an end;' each of thefe he treats feparately, and, after fome reflections on Sir Ifaac Newton's definitions, he fhews that all motion is produced and continued by action. Action,' Mr. Young fays, depends upon, and implies, the prefence of a fubftance which is active; and he concludes, that there is

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therefore throughout nature an ACTIVE SUBSTANCE, the conftituent effence of matter, and immediate natural agent in all effects.'

Our author next examines fome of the opinions of former metaphyficians, efpecially of Berkley, Locke, and Bofcovick. He then proceeds to fhew, that his active substance is an immaterial exiftence, not mind, but intermediate, and related to matter and mind.' It may be neceffary that we should here infert Mr. Young's definition of mind-mind is a fubftance which thinks.'

Having in the first part of his work established the exiftence of the active fubftance, the author treats, in the second, of action, and the manner in which the active substance produces matter and motion, inveftigated by inferences from effects to

caufes.'

The first chapter is On the rules of reafoning from effects to their caufe.' Here the author attacks Sir Ifaac Newton's rules of philofophizing; he fays, they are inadequate to the more extended purfuits of rational investigation;' and again, there is a fundamental deficiency in thefe rules, a deficiency which expofes us to every fort of delufion and error; they only direct us to follow a fingle path, rather than many, and command that this path fhould be the right one, but give us no marks whereby we may diftinguifh the right path from many others which are wrong.'

Inftead of thefe four deficient rules, which expofe us to delufion and error, our author gives five of his own, for which we refer our readers to the book. We obferve that Mr. Young offers a deficient and erroneous tranflation of Sir Ifaac's fourth Tule. The original is: "In philofophia experimentali, propofitiones ex phænomenis per ductionem collectæ, non obftantibus contrariis bypoth fibus, pro veris aut accurate aut quam proxime haberi debent, donec alia occurrerint phænomena, per quæ aut accuratiores reddantur aut exceptionibus obnoxia." Mr. Young's tranflation: Propofitions, collected by induction from phenomena, are to be admitted before any contrary hypothefes.'

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The next chapter explains in what manner the active fubfane is active, and how it acts,' viz. by uniting itself with the fubftance on which it acts."

On the

The titles of the fucceeding chapters are as follow: different origins and circumftances of activity in bodies apparent from obfervation.'--Of activity in the general, confidered as appertaining to bodies.'-' Of activity in bodies, as diftinguished into motion, and the two forms of impulfe, preffure and percuffion. Of the production of matter from its immaterial elements.' This is TOTALLY NEW, and contains a great variety of reasoning, according to the rules which Mr. Young had pre

viously

viously delivered.-'On the conftructive analogy between the primary corpufcles, the planets with their fyftems, the folar fyftem, and the fixed stars.'

The third part is, A further investigation of the nature and laws of the active or elementary fubftance:' and the fourth contains fome abridgments of the foregoing ideas, their agreement with facts, and conclufion.'

On the appearance of the fecond volume, in which the author intends to make practical applications of the theory here delivered, we fhall perhaps more fully understand his doctrine. In the mean time we fhall decline giving a decifive opinion of an unfinished work.

The following letter from Mr. Young is inferted to oblige him, and inform our readers of his intentions:

To the Authors of the Monthly Review..

Gentlemen,

If it be confiftent with the plan of your ufeful work, you will oblige me, and probably render an acceptable fervice to many of your readers, by tranfmitting to them the information I herewith take the liberty to fend you. It is my intention, in a fecond volume of my Effay on the Powers and Mechanifm of Nature, to make practical applications of the theory there laid down; and, as the very great difficulty and obfcurity of thefe important fubjects have given rife to much fpeculation and uncertainty, I wish to forward and facilitate their further elucidation: with this view, I propofe to allot a portion of the intended fecond volume, to the infertion of fuch critiques and remarks as may conduce to the removal of difficulties, by pointing out objections that merit to be obviated. This plan, I conceive, will tend much to bring forward an enquiry that must be interefting to every lover of fcience in this liberal and improving age. I am, Gentlemen,

May 20th, 1788, Warwick-court, Holborn.

Your very obedient, humble fervant,
R. YOUNG.

P. S. Such gentlemen as favour the author with their communications as propofed, will pleafe to comprife them in a moderate compafs, and tranfmit them before the 1st of October next.'

Though we have inferted the above, we mean not to take the leaft part in any controverfy that it may occafion, especially after having read the following paragraph in page 42 of this effay: If any one, without being able to prove these premiles erroneous, fhould yet infift on the folidity and impenetrability of matter, in the fenfe here contended againft, he must form his conclufion on grounds fo.different from thofe which direct my judgment, that it would be fruitlefs for me and fuch a perfon to debate the queftion.'

ART. XI. First Lines

of the Theory and Practice of Philofophical Chemistry. By John Berkenhout, M. D. 8vo. 6s. 6d. Boards. Cadell, 1788..

THE

HE laft twenty years have almost entirely altered the theory of chemistry. The labours and difcoveries of Bergman, Priestley, Cavendish, Kirwan, Scheele, Lavoifier, De la Metherie, and others, have in a great measure overturned the fyftems which were formerly reputed to be firmly established on the foundation of experimental facts. The existence and properties of the permanently elaftic fluids, opened a wide field to the view of the chemift and the natural philofopher. The doctrine of the elective attractions of bodies, first founded by Geoffroy, was raifed by Bergman into a fuperb monument that will perpetuate his memory to the latest potterity, and ferve as a memorial that he not only extended Geoffroy's plan, but that he brought it almost to a state of perfection.

The great change that was made in chemistry, by the difcovery of the different elaftic fluids, was effected by the fame ingenious and indefatigable man.

Paracelfus, whofe name is famous, as well for his abfurdities as for his great abilities, appears to have been the first philofopher who applied his thoughts to the confideration of the elaftic fluids. His difciple, Van Helmont, pursued the fame fubject, and apparently with greater fuccefs than his master; he appropriated the word Gas to the fe fluids, feveral of which he obferved and described; viz. Gas Ventofum. which feems to be the atmospheric air. 2d. Gas Sylveftre, which by the prefent philofophers is called fixed, fixable, or mephitic air; or aërial or atmospherical acid. 3d. Gas Pingue, or the inflammable ar. 4th. Gas flammeum, which feems to have been the dephlogifticated air. Befide the peculiar airs of the Grotto del Cane, of mines, of cellars, &c.

Mr. Boyle, and Dr. Hales, made various experiments with thefe different fluids; no material improvement, however, feems to have taken place before the time of Dr. Black, who in 1755 publifhed his experiments, fhewing the nature and properties of the elaftic fluid, which he called fixed air. About the year 1771, Bergman found that the fixed air was an acid fui generis,

* Our readers must pardon us if we detain them a little limine in primo, while we remark the impropriety of Firft Lines. Haller intitled his Phyfiology Prime Linea, an expreffion utually applied to painting, fignifying Out Lines, Firft Sketches, &c. It has, however, been adopted in literal English, by many medical writers, and other authors, who write Firft Lines, where Out-lines would be more proper. What objections could be made to Elements, Principles, or Rudiments? Di. Berkenhout has published Out-lines of Natural Hiftory.