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tical works upon this fubject, they may fairly be admitted to contain the most acceffible store of information which perfons ignorant of the science can at prefent command. They are delivered, as much as poffible, in the analytical mode. They take for granted no previous acquaintance with fcience in the learner; and they require, less than any work which we know, the afliftance of apparatus. Dr Black's manner of introducing the newly difcovered fübftances, has, indeed, no great appearance of fyftematic arrangement; but it fhould be remembered, that an elementary treatise has other objects in view, than the attainment of that fair outfide which forms the chief attraction of philofophical fyftems. After a perfon, wholly ignorant of science, has ftudied chemistry in thefe volumes, he may have occafion for fome fuch work as Lavoisier or Fourcroy, in order to digest and arrange the knowledge he has picked up. But, we believe, every one in the leaft converfant with the matter, will admit the impracticability of initiating an ignorant perfon into the fcience, merely by the ailiitance of thofe elegant and curioully fyftematic authors. It is true, we have fometimes felt inclined, in reading this work, to fufpect Dr Black of too great contempt for the fynthetic form. of inftruction. Upon this important point, however, his own arguments, as he delivered them in converfation with Dr Hutton and Mr Robifon, have been preferved; and we very willingly tranfcribe them, às containing a full and plain statement of the. principles on which the whole courfe was conftructed. Mr Robifon had expreffed a very favourable opinion of Lavoifier's sketch of a fcientific arrangement; and had alluded to the happy train of fynthetic deduction which it enabled that philofopher to carry through the whole chemical hiftory of bodies-.

“This, " faid Dr Black; " is the very thing I dislike it for. Chemiftry is not yet a fcience. We are very far from the knowledge of first principles. We should avoid every thing that has the pretenfions of a full fyftem. The whole of chemical science should, as yet, be analytical, like Newton's Optics; and we should obtain the connecting printiple, in the form of a general law, at the very end of our induction, as the reward of our labour. You blamed, and, in my opinion, justly, De La Grange's Mechanique Analytique, for being the very oppofite to a real analytical procefs;for adopting as the fundamental propofition, as a first principle, a theorem which in fact is nothing more than a faga, cious obfervation of an univerfal fact, discoverable indeed in every mé. chanical phenomenon; but fill not a principle, but the mathematical and not the phyfical refult of all our inductions. This is not a fundamental theorem, fit for inftructing a novice in the science, but for adepts alone. The cafe is the fame in chemistry.

"But this is not the greatest fault in the arrangement which fete out from the conftitution of the atmosphere. In order to get the proofs on which the validity of this firft principle mut entirely reft, we mutt VOL. 111. 20. 5. B

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fall to work with a number of complex, very complex fubftances, of which we know nothing, and whofe modes of action are among the moft mysterious things in chemistry; and the conclufions which we must draw, require a fteadinefs and contention of thought which very few poffefs, which a beginner in philofophical investigation cannot poffibly poffefs. It is by no means fair to appeal to a Lavoifier, a Cavendish, or a Berthollet, or other great chemifts, for the clearness of the evidence. They are not the proper judges. Lay it before a fenfible metallurgift, ignorant of chemistry. Afk this man whether he fees the incontrovertible force of the proof. When I take the matter in this light, I affirm, that even to a philofopher, the proofs of the fundamental propofitions which have been acquiefced in by the authors of this arrangement, are very fcanty, very flight and very refined. This is a fault in a system. published for the inftruction of the ignorant; and, in the prefent day, it is a very great fault. There is jult now a rage for fyftem,-for complete fyftems. We have got fuch a high conceit of our knowledge, that, we cannot be pleafed with a fyftem which acknowledges any imperfection: It muft not leave one open link: It must not leave any thing unexplained. And I fee it always happen, that if the application of a fyftem to the explanation of phenomena be very comprehenfive, leaving nó blanks, and if the explanation have fome feafibility, this catches the fancy, it dazzles the understanding. Nay, we think it impoffible that a principle that is falfe can tally with fo many phenomena. This feeming coincidence is confidered as a proof of its validity; and we are no longer folicitous about the dired proofs adduced in the beginning. I have often heard fuch arguments for what I knew to be great nonfenfe. This kind of authority accruing to a theory from its fpecious and extenfive application to phenomena, is always bad; and, with mere beginners in philofophy, it is doing them an irreparable hurt. It nourishes that itch. for theory; and it makes them unfolicitous about the first foundations of it-thus it forms in their minds the worst of all philofophical habits.

"I am refolved to go on in a very different way. I fubfcribe to almoft all Mr Lavoifier's doctrines; and I will teach them all. And I affirm that I fhall teach them with an impreffion of their truth which his method can never make. My ftudents fhall get all these doctrines piecemeal-every one of them by fteps which fhall be quite eafy and confident, because they shall be acquainted with every fubftance before I employ its phenomena as proofs. Each of Mr Lavoifier's doctrines fhall arife in course, as a fmall and obvious addition to the properties of fome fubftance already known. Then I shall carry the student back, and fhew him that the influence of our new difcovery extends alfo to thofe fubftances which we had been confidering before. Thus, all the doctrines will be had eafily, familiarly, and, with confidence in their truth.

"I even think that this method will be more pleasant,—the novelties, or reformations, being, by this method, diftributed over the whole courfe. And it will have yet another advantage: It will make the ftudent acquainted with the chemistry of former years, which is far from being unworthy of the attention of a philofopher. Newton, Stahl, Margraaf, Cramer, Scheele, Bergmanp, were geniufes not below the

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common level. But the perfon who learns chemistry by Lavoifier's fcheme, may remain ignorant of all that was done by former chemifts, and unable to read their excellent writings.

"I do not find that my old arrangement needs much change: Some I will make,-chiefly in the order in which I treat the inflammable subftances and the metals. "

We have already mentioned, in general terms, the great additional value which Mr Robifon's notes confer upon this publication. Beides a variety of curious and original chemical facts, they illuftrate, by feveral very important documents and acute reafonings, the hiftory of Dr Black's difcoveries. They answer the demand which was long ago made by Mr Nicolfon, that fome contemporary author fhould adjust the claims of the feveral philofophers who have borne a part in establishing the doctrine of latent heat. They prove to a demonftration, that the undivided honour of this grand difcovery is due to the author of these Lectures, whofe amiable and dignified modefty prevented him from taking the necessary steps to fecure his own claims. The following statement of the attempts that have been made to rob him of his juft fame, prefents no very pleafing picture of the philofophical character; and we are almost inclined to hope, that Mr Robifon, from whom our authority is derived, has been mistaken in his deci

We feel it our duty, however, to give the circumstances to the public as he has detailed them; premifing that we are forry we can fee no immediate reafons for doubting his accuracy, while we rely most implicitly on his veracity and candour..

Dr Black never published his own account of the discovery, but he gave it every year after 1760, in his Lectures, to very numer ous claffes of ftudents from various parts of Europe. It is proved, from his note-books, as well as from the concurring teftimony of Meffrs Robifon and Watt, that he completed this difcovery, as far as regards aqueous fluidity, between the years 1754 and 1757. We have already remarked, that he immediately extended it to the cafe of aëriform fluidity, even before he had actually performed the experiments by which the application is illuftrated in detail. Among his pupils, Dr Black had many gentlemen of Geneva y particularly a M. Chaillet, in 1763, and a Dr. Odier, who com refponded with M. De Luc, and communicated to our country man feveral of that gentleman's meteorological obfervations. A Swedish gentleman, of the name of Willems, or Willemfon, (from Stockholm), was alfo much in the company of Dr Black and his friends, about the year 1768. He was wholly occupied with chemical ftudies.. From none of thefe ftudents was the fighteft hint ever obtained, that a doctrine in any degree relembling that of latent heat, had been known in Geneva or Sweden. While

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**Translation of Fourcroy, 27. fe&t. of the valuable Note to Pt. I. ch. 5. § 2.

While the communication between this country and thofe parts was thus conftant, manufcript copies of Dr Black's lectures were in very general circulation among his ftudents. They were even fold at a moderate price; and they contained accounts of his discoveries, if not altogether correct, at least abundantly copious for all the purposes of plagiarifm. In 1770, a furreptitious publication of them was made by a London bookfeller, under a general title; and this work gave a very diftin& statement of the leading parts of the doctrine, with a full acknowledgement that Dr Black was the discoverer. In 1772, Mr Wilcke of Stockholm read a paper to the Royal Society of that city, in which the abforption of heat, by melting ice, is defcribed; and in the fame year, M. De Luc of Geneva, published his Recherches fur les modifications de l'Atmosphere, in which the doctrine is, with much lefs accuracy, employed to explain fome meteorological facts.

Our readers will probably have anticipated the conclusion which this statement of circumstances forces us to draw,-that both the one and the other of these gentlemen, in all probability, owed their knowledge of the abforption of heat to the diffufion of Dr Black's difcovery, through the medium of his Lectures. But the fubfequent conduct of M. De Luc deferves our farther attention; and leaves as little doubt, with refpect to his culpability, as can exift upon a queftion of this fort.

About the year 1782, Dr Black was informed, that M. De Luc earnestly wished to become the editor of his obfervations upon latent heat, in order to fecure Dr Black's claims to the discovery, from the attempts which were continually made by others to appropriate it. In confequence of repeated folicitations, Dr Black gave his friend Mr Watt permiffion to communicate the leading points of his theory, and inftructions to perform the experiments before M. De Luc. Neither the Doctor nor his friends had now the smalleft anxiety upon the fubject: they trufted in the promife of the Genevefe philofopher, and expected to fee in his great work, a full vindication of the claims which he had anxioufly volunteered to defend. The publication at last arrived; and the mode of defence was fomewhat novel. It confifted in a refutation of the claims urged by others, and an affertion, that the discovery of latent heat was entirely M. De Luc's own, Dr Black being only allowed the merit of having first attempted to measure the exact quantity of abforption in the particular cafe of aqueous fluidity. Mr Watt then wrote a letter to M. De Luc, containing a full explanation of Dr Black's discovery, and infifted that this fhould be published in the next volume of the work. It appeared accordingly; but was accompanied only by an acknowledgement of the fatisfaction which M. De Luc received, from learning that his own system had so able a defender as Dr Black;

a circumftance, he adds, which will give him new confidence in the doctrine.

From the foregoing statement, then, it appears, that M. De Luc publifhed a work, containing a few crude ideas on the combination of heat; that he afterwards became better acquainte ed with the fubject; that he formed a defign to pafs for the author of the doctrine, by completing his knowledge of the theory, and twisting his former vague statements into fome kind of Gmilarity; that, for this purpofe, he applied to the man whom he knew to be the difcoverer, and obtained, from him, a full account of the matter, under the pretext of defending his claim a gainst others; that, instead of fulfilling his promise, he only refuted the claims of thofe others, in order to bring forward his own; converted the documents which he had procured, to his own ufe; and concluded by politely laughing at the person whom he had thus defrauded. Such is the amount of the impreffion made by Mr Robifon's narrative, in the eighth note to the first volume. We wish that fome friend of the Genevefe philofopher could ftep forward to clear him from fo foul a charge. We are willing to hope, that his conduct may be explained in a way confiftent, at least, with the belief of his honefty; for who can hefttate to pronounce, that the conduct here imputed to him, would have been deemed common imposture, if avarice, not vanity, had been the motive, and money, not fame, the end?

Mr Robifon has incorporated with the text of thefe Lectures, vol. II. p. 215, fome very curious obfervations upon the conduct of Lavoisier and his affociates, both towards Dr Black, and in the eftablishment of their new chemical fyftem. We rejoice that this fubject is fairly brought before the public; and, on whichever fide the decifion may finally be given, the hiftory of the science, as well as the political hiftory of the times, is likely to be illuftrated by the difcuffion. That the Frence chemifts formed themselves into a junto for the propagation of their fyftem; that, like all juntos, they delivered their doctrines with an authoritative tone, highly indecorous in matters of science; and that they even difplayed fomewhat of a spirit of perfecution towards those who, from ancient habits, or from a predilection for their own new theories, refufed their affent to the antiphlogistic doctrines, are facts which cannot be difputed. As little can it be denied, that the Parifian philosophers, animated, like all fimilar affociations, by an efprit de corps, and mingling with this, very strong national partialities, arrogated to themselves the merit of every important difcovery, nay, of almost all the detached obfervations, which had been made in any part of Europe, during the latter half of the eighteenth century. Now, Mr Robifon requires us to go a step farther, and to admit

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