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being abundantly furnished with matter, his conversation was at all times pertinent and agreeable : for Dr Black's acquirements were not merely those of a man of science. He was a stranger to none of the elegant docomplishments of life. He therefore easily fell into any topic of conversation, and supported his part in it respectably. He had a fine, or accurate musical ear, and a voice which would obey it in the most perfect manner; for he sung, and performed on the fute, with great taste and feeling ; and could fing a plain air at fight, which many, instrumental performers cannot do. But this was science. Dr Black was a very intelligent judge of musical composition ; and I never heard any person expreso so intelligibly the characteristic differences of some of the national musics of Europe. I speak of Dr Black as I knew him at Glasgow: After his coming to Edinburgh, he gave up moft of those amusements. Without having studied drawing, he had acquired a confiderable power of expression with his pencil, both in figures and in landscape. He was peculiarly happy in expressing the pasốons; and seemed, in this respect, to have the talent of a hiltory painter. He had not had any opportunities of becoming a connoiffeur ; but his opia nion of a piece of painting, or sculpture, was respected by good judges. Figure, indeed, of every kind, attracted his attention ;-in architecture, furniture, ornament of every fort, it was never a matter of indifference. Even a retort, or a crucible, was to his eye an example of beauty or deforinity. His memorandum-books are full of studies (may I call them) of this fort ; and there is one drawing of an iron furnace, fitted up with rough unhewn timber, that is finished with great beauty, and would not disgrace the hand of a Woollet. Naturally, therefore, the young ladies were proud of Dr Black's approbation of their taste in matters of ornament. These are not indifferent things : they are features of an elegant mind, and they account for some part of that satisfaction and pleasure which persons of all different habits and pursuits felt in Dr Black's company and conversation.

I think that I could frequently discover what was the circumstance of form, &c. in which Dr Black perceived or fought for beauty it was some suitableness or propriety; and he has often pointed it out to me, in things where I never should have looked for it. Yet I saw that he was ingeniously in the right. I may almost say that the love of propriety was the leading sentiment of Dr Black's mind. This was the firit standard to which he appealed in all his judgements ; and I believe he endeavoured to make it the directing principle of his conduct. Happy is the man whose moderation of purtuits leaves this sentiment in poffeffion of much authority. Seldom are our judgements greatly wrong on this queftion ; but we too feldom listen to them.' Preface, p. lxvi. lxvii.

The following extract describes Dr Black's merits as a Lecturer, with a truth and precision which every one will immediately feel who has had the happiness of receiving instructions from that eminent teacher. The sustained elegance and propriety which A 4 ..

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we have already taken notice of, as characteristic both of his original inquiries, and of his demeanour in the ordinary affairs of life, was equally conspicuous in this favourite line of exertion. .

· Dr Black now formed the firm resolution of directing his whole ftudy to the improvement of his scholars in the elementary knowledge of chemistry. He saw too many of them with a very scanty stock of previous learning. He had many from the workshop of the manufacturer, who had none at all ; and he saw that the number of such hearers muft increase with the increasing activity and prosperity of the country : And these appeared to him as by no means the least important part of his auditory. To engage the attention of such pupils, and to be perfectly understood by the most illiterate, was therefore considered by Dr Black as his most sacred duty. Plain doctrines, therefore, taught in the plaineft manner, muft employ his chief study. That no help may be wanting, all must be illustrated by suitable experiments, by the exhibition of specimens, and the management of chemical processes. Nice and abstruse philosophical opinions would not intereit such hearers ; and any doctrines, inculcated in a refined manner, and referring to elaborate disquisitions of others, would not be understood by the major part of an audience of young persons, as yet only beginning their studies.

To this resolution Dr Black rigidly adhered, endeavouring every year to make his courses more plain and familiar, and illustrating then by a greater variety of examples in the way of experiment. No man could perform these more neatly and successfully. They were always ingeniously and judiciously contrived, clearly establishing the point in view, and never more than sufficed for this purpose. While he scorned the quackery of a Mowman, the fimplicity, neatness, and elegance, with which they were performed, were truly admirable. Indeed, the fimplex munditiis stamped every thing that he did. I think it was the unperceived operation of this impression that made Dr Black's lectures such a treat to all his scholars. They tvere not only instructed, but (they knew not how) delighted; and without any effort to please, bet solely by the natural emanation of a gentle and elegant mind, cooperating, indeed, with a most perspicuous exhibition of his sentiments, Dr Black became a favourite lecturer; and many were induced, by the report of his students, to attend his courses, without having any particular relish for chemical knowledge, but merely in order to be pleased. This, however, contributed greatly to the extending the knowledge of chemistry ; and it became a faflıionable part of the accomplishment of a gentleman.' Preface, p. 1. li.

One prominent feature in Dr Bluck's character, Mr Robison does not appear to have delineated with sufficient strength: we mean the want of pallion. There can be no doubt that this defeet, however much it may have contributed to the ease and calmness of his enjoyments, deprived his mind of that energy by which alone the greatet! things are periormed in the pursuits

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either' of speculation or of active life. When we consider how short a period of time his original inquiries occupied, how carelessly he left his discoveries to be appropriated by others, how little progress he made in following out those sublime ideas, by the help of which his followers have overturned and created fyfa tems; nay, how long an interval he frequently suffered to elapse between the conception and execution of some experiment which was to decide the truth of a favourite theory; we must be convinced that he felt little of the infpiration so necessary to the full success of those happy few who poffess all the powers of philofophical investigation. This want of passion, or of ardour and energy, or, to give it the right name, this indolence, was confpicuous in all the particulars of Dr Black's conduct. The discovery which he first made, was the last of being completed. He never could be induced to publish any account of it to the world, notwithstanding the constant attempts of his rivals to deprive him of the claim. He was at all times averse to publication, and fartidious, to an uncommon degree, in his judgements of his own compositions. When the experimentum crucis of his doctrine of latent heat occurred to him, he delayed making it for many months, because there happened to be no icehouse in the town where he lived. In extending this doctrine to the case of aëri. form fluidity, he remained for years satisfied with analogies and rough sketches of experiments, which he could at any time have performed with ease; and however little doubt he had reasori to entertain of the result, he evinced none of that anxiety, which is so natural to a discoverer even on the least important points of his theory. After ascertaining the existence of fixed air, and de. termining some of its qualities, he delayed investigating its other properties, and pursuing the most obvious experiments on analogous bodies ; until the field was occupied by others, who, with scarcely a spark of his truly philosophical genius, were enabled, by their superior activity, to make the most valuable discoveries. Nor can we avoid remarking how closely his propriety and correctness of character was connected with this freedom from pasion, which always left his mind, as it were, disengaged, unabsorbed by any predominant enthugasm, and at leisure to regard the most trivial concerns. He was never, like Newton or Smith, known to be absent in society; or thoughtless and playful in his hours of relaxation, like Hutton and Hume.

" As Dr Black,(we quote the words of his near relation Dr Ferguson *) “ had never any thing for oftentation, he was, at all times,

precisely . * Mr Robifon has incorporated with the narrative contained in his Preface, several extracts from a biographical sketch of Dr Black, drawn up by this eminent writer.

precisely what the occasion required, and no more. Much as he was engaged in the details of his public station, and chemical exhibitions, his chambers were never seen lumbered with books and papers, or fpecimens of mineralogy, &c. or the apparatus of experiments. Nor did any one see Dr Black hurried at one time to recover matter which had been improperly neglected on a former occasion. : Every thing being done in its proper season and place, he ever seemed to have leisure in fore ; and he was ready to receive his friend or acquaintance, and to take his part with cheerfulness ia any conversation that occurred. And let me remark, that no one ever with more ease to himself refrained from professional discussions of any fort, or conversation in which he was acknowledged superior,-or with less self-denial, in mixed company, left the subje& of conversation to be chosen by others.” Preface, p. lxviii.

His attention was awake, even to the mere trifles of life. His domestic affairs were regulated with an attention to minute circumstances, rarely to be observed in the household of a philosopher; and the fortune which his admirable economy enabled him to amass (notwithstanding various diminutions that his income suffered from his liberal and friendly disposition), was accurately bequeathed to his near relations, in shares proportioned to the degree which each individual possessed of his esteem. He was often heard to express anxiety with respect to the mode of his death, and to wish for a quiet departure from this world, without the evils of a long continued fick-bed. It is singular how characteristic of the man, and how suitable to such feelings, this last scene actually proyed.

« On the 26th November 1799, and in the seventy-first year of his age, he expired, without any convulsion, shock or itupor, to announce or retard the approach of death. Being at table, with his usual fare, some bread, a few prunes, and a measured quantity of milk, diluted with water, and having the cup in his hand when the last stroke of his pulse was to be given, he had set it down on his knees, which were joined together, and kept it deady with his hand, in the manner of a person perfectly at cafe ; and in this attitude expired, without spilling a drop, and without a writhe in his countenance ; as if an experiment had been required to New to his friends the facility with which he departed. " * His servant opened the door to tell him that some one had left his name ; but, getting no answer, stepped about half way towards him, and feeing him fitting in that easy pofture, supporting his baron of milk with one hand, he thought that he had dropped asleep, which he had sometimes feen happen after his meals.' He went back, and hut the door ; but before he got down stairs, some anxiety, which he could not account for, made himn return and look again at his master. Even then, he was fatisfied, after coming pretty near him, and turned

to * The first part of this extract is taken from the Memoir of. Dr Ferguson.

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to go away ; but again returned, and, coming quite close to him, he found him without life.' Preface, Ixxiv. lxxv.

Such was the man, of whose lectures the volumes now before us contain a faithful tranfcript. They are, therefore, a most valuable ac qui:ition, alır. ugh we should allow them only the merit of a literary curiosity, a relique of the greatest inductive philosopher that has appeared Gince the days of Sir Isaac Newton, and, unfortunately, one of the very few monuments which his modelty and his indolence permitted him to leave. But this publication is highly important in another point of view; it contains the only history which we have of the discovery of latent hear, and a much more copious account of the discovery of fixed air than that which the author publilhed during his life.

The former of these discoveries is, in our opinion, the most important in its consequences, and the most hgual, with regard to difficulty, of any that has been made since the application of gravity to explain the laws of planetary motion. It differs from all the others, with which we are acquainted in this material refpect, that it is separated, by a vast interval, from the previous

leps of our knowledge. By how many infenfible gradations did we arrive at the doctrine of the composition of water? First, the inflammation of certain vapours was observed ; then, the disa covery of fixed air having taught philosophers to examine the properties of certain elastic fluids, one of these was found to differ from the rest in being inflammable. It was afterwards remarked, that this air, when lowly burnt, produced moisture up. on a cold body held over the plane : fixed air was, by fome, thought to be produced in the lame process: and reasoners, inferred froin hence, that the water had been contained in the in. flammable air. But others varied the experiment, and burned the air in close veffels; moisture was still formed, and accurate observation showed that no new zëriform product resulted from the combustion. A new species of air having been discovered, much better calculated than common atmospherical air to support flame, the combustion of inflammable air was tried with this new spe. cies, and it was found to be extremely rapid. The combustion being performed in close vefels, the inaccuracy of the experiment gåve rise to various errors; but water was always found to be produced, and some ingenious men, particularly Mr Watt, realoning from all these facts, concluded that this fluid is a compound of the two airs, deprived, by their union, of a confiderable portion of their latent heat, the quantity (viz.) which is ne. cettary for maintaining the elastic aëritorm state. This idea was verified by the accurate experiment of Mr Cavendilh, in which the quantity of water formed was compared with the quantities of the airs burnt; and the French chemifts added new proofs of

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