Zurich, he had not the fmalleft notion of the fciences, or of elegant literature, and confequently no tafte for ftudy. The first incident that developed a hidden germ of philofophical genius, was his meeting with Wolf's metaphyfics; this was the birth of his tafte for fcience; but he wanted a guide. The clergyman with whom he lodged was (no uncommon thing!) an ignorant man, and the academical prelections were, as yet, above the reach of his comprehenfion. On the other hand, a fedentary life was not the thing he liked, nor to which he had been accustomed; and, morcover, a fociable turn of mind led him often into company, where he loft much time in frivolous amufements, yet without corrupting his morals. Who, that obferved him, fays Mr. Formey, at this period, would have thought that SULZER would one day be numbered among the moft knowing and wifeft men of his time? The learned Gefner was the inftrument of Providence, that rendered Sulzer's inclination to study triumphant over his paffion for amufement and company. Animated by the counfels and example of this worthy and learned man, he applied himself to philofophy and mathematics with great ardour, and refumed the purfuit of Grecian literature and the Oriental languages. The contemplation of nature became his noble and favourite paffion. An ecclefiaftical fettlement in a rural fcene, that exhibited happy objects and occafions for this delightful ftudy, began to render his days happy and ufeful; and he published, in 1741, Moral Contemplations of the Works of Nature; and, the year following, an Account of a voyage he had made through the Alps; which fhewed, at the fame time, his knowledge of natural hiftory, and the taste and fenfibility with which he furveyed the beauties of nature, and the grandeur and goodnefs of its author. He afterwards became private tutor to a young gentleman at Magdeburg. This procured him the acquaintance of Meffrs. Maupertuis, Euler, and Sack, which opened to his merit the path of preferment, and advanced him fucceffively to the place of mathematical profeffor in the King's College at Berlin, in 1747, and to that of member of the Royal Academy in 1750.

In this last quality he diftinguifhed himself in a very eminent manner, enriched the clafs of Speculative Philofophy with a great number of excellent memoirs, and was justly confidered as one of the first-rate metaphyficians in Germany. But his genius. was not confined to this branch of fcience. His Univerfal Theory of the Fine Arts, is a capital production. A profound knowledge of the arts and fciences, and a perfect acquaintance with true tafte are eminently difplayed in this work, and will fecure to its author a permanent and diftinguifhed rank in the republic of letters. The first volume of this excellent work was published in 1771, and the second in 1774. We fhall

not.

not here give a catalogue of the writings of M. Sulzer; but we cannot help mentioning his Remarks on the Philofophical Ef fays of the late Mr. HUME, as a work of real merit, which does juftice to the acuteness, while it often detects the fophiftry of the British Bayle. The moral character of M. SULZER was amiable and virtuous: fociability and beneficence were its characteristical lines; and his virtues were animated by that facred philofophy that forms the Chriftian, ennobles man, and is the only fource of that heart-felt ferenity and fedate fortitude, which fupport humanity, when every other object of confidence fails. His dying moments were calm, humble, and fublime; and when he expired, the placid and compofed air of his countenance made his mourning friends doubt, for fome time, whether it was death, or fleep, that had fufpended his converfation. He had no enemy; and his friends were numerous, affectionate, and worthy of the tender returns he made them.

The king of Pruffia diftinguished him by repeated marks of munificence and favour. We learn, however, with some furprife, from the eulogy before us, that his royal protector had never feen him before the end of the year 1777, though he had been member of the academy from the year 1750. The audience, indeed, though late vouchfafed, was honourable to M. Sulzer, with whom the monarch converfed for a long time with the greatest affability and condefcenfion.

EXPERIMENTAL PHILOSOPHY.

Mem. I. An Acount of fome Attempts to obtain Kunkel's Red Glafs, already coloured, when taken from the Crucible. By M. MARGRAFF. Kunkel's glafs is always white and transparent when it comes from the crucible, and only affumes its beautiful red colour when it is warmed at a flame.

Mem. II. Experiments relative to a new Method of disengaging the Copper from the Mine. By the fame. The celebrated M. Pott is faid to have discovered a method of disengaging the copper from its mine by one fingle fufion, and to have died without communicating to any perfon the means he employed for this purpose. At the earnest defire of the late M. Sulzer, our Academician made feveral trials of this kind, and fucceeded. He describes his procefs in this Memoir.

Mem. III. A new Method of extracting Pruffian Blue from all kinds of Cobalt, for the use of China Manufactures. By M. GER

HARD.

Mem. IV. Concerning a new Method of producing, with a very fmall quantity of Coals, or other inflammable Subftances, a Heat equal to that which is obtained by Mirrors and Burning-glaffes of a confiderable fize: Together with the Defcription of a Stove, which, while it warms an Apartment, purifies the Air which it contains, by depriving it of its Phlogifion. By M, ACHARD, It was by tranfmitting

mitting a current of dephlogifticated air through burning coals, that our ingenious Academician produced a quantity of heat which the burning body could not have produced in the common atmospherical air, which always contains a certain quantity of phlogifton; and in proportion to this quantity is lefs proper to accelerate inflammation, as the experiments of Dr. Priestley, often repeated by others, abundantly teftify. We refer our Readers to the Memoir for an account of M. ACHARD'S Experiments relative to this object. Dephlogisticated air may be obtained in large quantities, with little trouble, and at a very fmall expence; and every kind of air may be eafily deprived of its phlogifton, as M. ACHARD has fully fhewn in this Memoir, and in another contained in the preceding volume. Common air, tranfmitted by a bellows through fufed nitre, lofes all its phlogifton by its imperceptible detonation with the nitrous acid, fo that it comes dephlogisticated out of the bellows. The quantity of heat that was added to the flame of a fmall lamp, by conveying to it a current of dephlogifticated air, melted, in two feconds, a rod of iron one-fifth of an inch in diameter, and made it diffolve in burning drops; but still greater effects were produced by coals.

Befides the advantages, with refpect to the production of an intense heat, that natural philofophy and chemistry may reap from the dephlogiftication of common air, effectuated by its tranfmiffion through nitre in fufion, this operation may be em ployed for a purpofe equally important, and in which it will be of more general utility: for, by it, the dephlogiftication of the air of an apartment may be carried to any degree that may be judged expedient. The confequence of which this may be to health and fpirits is not at all dubious. It is well known how both are promoted by the purity of the air which we breathe; and our academician has obferved hypochondriac persons pafs from a ftate of gloomy anxiety to a state of ferenity and comfort, by paffing from the common air into an apartment where the air had been dephlogifticated. He gives here an ample description of the eafieft method of freeing the air of a room of its phlogifton, in any degree that may be defired. In this method, the fame ftove that warms the apartment is employed in melting the nitre: and as this would render the operation impracticable, or at leaft intolerable, at certain times of the year, when the weather is temperate or warm, on account of the degree of heat required in the ftove to fufe the nitre, M. ACHARD indicates a very ingenious method of remedying this inconvenience. We recommend the perufal of this memoir, in a particular manner, to thofe who are concerned in the direction of hofpitals, where noxious air fo often baffles all the efforts of the phyfician. All we can do is, to indicate the fources of APP. REV. Vol. lxv. ufeful

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ufeful information.-Want of space must often hinder us from entering into particulars.

Mem. V. Concerning the Analogy that there is between the Production and the Effects of Electricity and Heat; as alfo between the Property in Bodies by which they conduct the electrical Fluid, and that which renders them fufceptible of Heat. To which is added, the Defcription of a new Inftrument, adapted to measure the Quantity of the electrical Fluid which is conducted by Lodies of a different Nature placed in the fame Circumftances. By M. ACHARD. This is no more than a fhort abridgment of an ample memoir, which the indefatigable academician has compofed upon this curious fubject. It is divided into three parts. In the firft, M. ACHARD endeavours to prove, that the production of electricity is fimilar to the production of heat.- In the fecond he fhews, that the effects produced by the electrical fluid are analogous to thofe produced by the igneous fluid. In the third he proves, that there is a perfect resemblance between the aptitude of bodies to conduct the electrical fluid, and their aptitude to receive heat.

In the firft part, the point of refemblance is rubbing or friction, by which both electricity and heat are produced. It may be objected, that the analogy here is not perfect; fince metals, and the bodies which are generally confidered as con-ductors, become electrical, according to the notion commonly received, only by their contact with bodies originally electrical, which are rubbed; and that the rubbing, directly, thefe bodies (the conductors), cannot render them electrical. In order to anfwer this objection, M. ACHARD remarks, that when a body, originally electrical, is electrified by being rubbed against a body which is a conductor, the latter, when infulated, exhibits figns of electricity, as palpable as those which are given by the body that is electrical per fe. Now, fays he, this electricity is not communicated to the conductor by the body that is originally electrical, because it is negative in the conductor, when the electricity of the original electric is pofitive, and vice verfâ. After having laid down the theory that is deducible from this obfervation, and is confirmed by facts, our author concludes, firft, that rubbing always produces electricity in all cafes, of whatever nature the bodies may be; and that when the electricity is not palpable, this only proceeds from its being loft in the very moment that it is produced:-fecondly, that there is no body, which, being rubbed against another that tranfmits the electrical Auid with more or lefs difficulty, does not exhibit marks of electricity; and that metals are as electrical in hemfelves (per fe) as glafs and refins. (This propofition, fays our author, is only contradictory in appearance-the contradiction will vanifh on a close examination.)

Thirdly,

-Thirdly, that as rubbing always, and in all cafes, produces electricity, the analogy between the production of heat and electricity is perfect.

In the fecond part, the points of refemblance between the effects produced by heat and electricity are as follows: 1. They both dilate all bodies. 2. They both accelerate vegetation and germination; and it is remarkable, that pofitive electricity accelerates vegetation as much as negative: from whence it follows, that the effects of the electrical fluid do not proceed from the augmentation or diminution of its quantity, `but from the repulfion of the parts of bodies, which have a degree. of electricity (whether pofitive or negative) different from that of the medium in which they are placed. 3. They both accelerate evaporation. 4. They both accelerate the motion of the blood in animals. 5. They both contribute to the formation and developement of the foetus in animals, as appears by our author's experiments on hens-eggs, formerly mentioned; and thofe made, by other naturalifts, on the eggs of the butterfly. -6. They both reduce metals, and other bodies, to a ftate of fufion. These, and other reafons, prove a great analogy between the effects of heat and electricity.

In the third part, the ingenious academician proves, from fome curious obfervations, that feveral bodies, which receive and lofe, with difficulty, their prefent degree of heat, receive alfo, and lofe, with difficulty, their electricity? Repeated and multiplied experiments are neceffary to determine, whether or not this law is general and without any exception. To make thefe experiments, and to compare bodies with refpect to their property of conducting the igneous and the electrical fluids, it was neceffary to have an inftrument capable of measuring and afcertaining the degrees in which bodies conduct electricity. Our academician thinks this a matter of great confequence towards the improvement of the theory of electricity; and is furprised that it has been hitherto entirely neglected. He has, therefore, conftructed an inftrument, by means of which ic will be poffible to afcertain, with great accuracy, the quantity of electricity which a body lofes in a given time, by touching another body that is not electrified. For the defcription and ufe of this inftrument we refer our readers to the memoir itself. M. ACHARD does not give us here an enumeration of the experiments he has made with it, nor their refults: but these we may expect in fome future memoir.

Mem. VI. Concerning the Changes which Earths, mixed with metallic and femi metallic Calxes undergo, when they are exposed to a Fire that produces Fufion. By M. ACHARD-This very curious and elaborate memoir is not fufceptible of abridgment.

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