being abundantly furnished with matter, his converfation was at all times pertinent and agreeable: for Dr Black's acquirements were not merely thofe of a man of fcience. He was a stranger to none of thei elegant accomplishments of life. He therefore easily fell into any topic of conversation, and fupported his part in it refpectably. He had a fine, or accurate musical ear, and a voice which would obey it in the most perfect manner; for he fung, and performed on the flute, with great tafte and feeling; and could fing a plain air at fight, which manyinftrumental performers cannot do. But this was fcience. Dr Black was a very intelligent judge of mufical compofition; and I never heard any perfon exprefs fo intelligibly the characteristic differences of fome of the national mufics of Europe. I fpeak of Dr Black as I knew him at Glasgow: After his coming to Edinburgh, he gave up moft of thofe amusements. Without having ftudied drawing, he had acquired a confiderable power of expreffion with his pencil, both in figures and in landfcape. He was peculiarly happy in expreffing the paffions; and feemed, in this refpect, to have the talent of a hiftory painter. He had not had any opportunities of becoming a connoiffeur; but his opinion of a piece of painting, or fculpture, was refpected 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 deformity. 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 difgrace the hand of a Woollet. Naturally, therefore, the young ladies were proud of Dr Black's approbation of their tafte in matters of ornament. These are not indifferent things; they are features of an elegant mind, and they account for fome part of that fatisfaction and pleafure which perfons of all different habits and pursuits felt in Dr Black's company and converfation.

I think that I could frequently discover what was the circumftance 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 fhould have looked for it. Yet I faw that he was ingenioufly in the right. I may almoft fay that the love of propriety was the leading fentiment of Dr Black's mind. This was the firft ftandard 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 whofe moderation of purfuits leaves this fentiment in poffeffion of much authority. Seldom are our judgements greatly wrong on this queftion; but we too feldom liften to them." Preface, p. lxvi. lxvii.

The following extract defcribes Dr Black's merits as a Lecturer, with a truth and precifion which every one will immediately feel who has had the happiness of receiving inftructions from that eminent teacher. The fuftained elegance and propriety which

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 confpicuous in this favourite line of exertion.

• Dr Black now formed the firm refolution of directing his whole ftudy to the improvement of his fcholars in the elementary knowledge of chemistry. He faw too many of them with a very fcanty flock 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 must increase with the increafing activity and profperity of the country: And these appeared to him as by no means the leaft important part of his auditory. To engage the attention of fuch pupils, and to be per fectly understood by the most illiterate, was therefore confidered by Dr Black as his moft facred duty. Plain doctrines, therefore, taught in the plainest manner, muft employ his chief ftudy. That no help may be wanting, all must be illustrated by fuitable experiments, by the exhibition of fpecimens, and the management of chemical proceffes. Nice and abftrufe philofophical opinions would not intereft fuch hearers; and any doctrines, inculcated in a refined manner, and referring to elaborate difquifitions of others, would not be understood by the major part of an audience of young perfons, as yet only beginning their ftudies.

To this refolution Dr Black rigidly adhered, endeavouring every year to make his courfes more plain and familiar, and illuftrating them by a greater variety of examples in the way of experiment. No man could perform thefe more neatly and fuccefsfully. They were always ingeniously and judiciously contrived, clearly establishing the point in view, and never more than fufficed for this purpose. While he fcorned the quackery of a fhowman, the fimplicity, neatness, and elegance, with which they were performed, were truly admirable. Indeed, the fimplex munditiis ftamped every thing that he did. I think it was the unperceived operation of this impreffion that made Dr Black's lectures fuch a treat to all his fcholars. They were not only inftructed, but (they knew not how) delighted; and without any effort to please, but folely by the natural emanation of a gentle and elegant mind, cooperating, indeed, with a moft perfpicuous exhibition of his fentiments, Dr Black became a favourite lecturer; and many were induced, by the report of his ftudents, to attend his courfes, without having any particular relish for chemical knowledge, but merely in order to be pleafed. This, however, contributed greatly to the extending the knowledge of chemistry; and it became a faflionable part of the accomplishment of a gentleman. Preface, p. 1. li.

One prominent feature in Dr Black's character, Mr Robifon does not appear to have delineated with fufficient strength: we mean the want of paflion. There can be no doubt that this defect, however much it may have contributed to the eafe and calmnefs of his enjoyments, deprived his mind of that energy by which alone the greatest things are performed in the pursuits

either of fpeculation or of active life. When we confider how fhort a period of time his original inquiries occupied, how carelefsly he left his difcoveries to be appropriated by others, how little progrefs he made in following out thofe fublime ideas, by the help of which his followers have overturned and.created fyftems; nay, how long an interval he frequently suffered to elapfe between the conception and execution of fome experiment which was to decide the truth of a favourite theory; we must be convinced that he felt little of the infpiration fo neceflary to the full fuccefs of thofe happy few who poffefs all the powers of philofophical investigation. This want of paffion, 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 difcovery which he first made, was the laft of being completed. He never could be induced to publifh any account of it to the world, notwithstanding the conftant attempts of his rivals to deprive him of the claim. He was at all times averfe to publication, and faftidious, to an uncommon degree, in his judgements of his own compofitions. 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 icehoufe in the town where he lived. In extending this doctrine to the cafe of aëriform fluidity, he remained for years fatisfied with analogies and rough sketches of experiments, which he could at any time have performed with eafe; and however little doubt he had reafon to entertain of the refult, he evinced none of that anxiety, which is fo natural to a difcoverer even on the leaft important points of his theory. After afcertaining the existence of fixed air, and determining fome of its qualities, he delayed inveftigating its other properties, and pursuing the most obvious experiments on analogous bodies; until the field was occupied by others, who, with fcarcely a fpark of his truly philofophical genius, were enabled, by their fuperior activity, to make the most valuable difcoveries. Nor can we avoid remarking how closely his propriety and correctness of character was connected with this freedom from paffion, which always left his mind, as it were, difengaged, unabforbed by any predominant enthusiasm, and at leifure to regard the most trivial concerns. He was never, like Newton or Smith, known to be abfent in fociety; or thoughtlefs 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, feveral extracts from a biographical sketch of Dr Black, drawn up by this eminent writer.

precifely what the occafion required, and no more. Much as he was engaged in the details of his public ftation, and chemical exhibitions, his chambers were never feen lumbered with books and papers, or specimens of mineralogy, &c. or the apparatus of experiments. Nor did any one fee Dr Black hurried at one time to recover matter which had been improperly neglected on a former occafion. Every thing being done in its proper feafon and place, he ever feemed to have leifure in ftore; and he was ready to receive his friend or acquaintance, and to take his part with cheerfulness in any conversation that occurred. And let me remark, that no one ever with more ease to himself refrained from profeffional difcuffions of any fort, or converfation in which he was acknowledged fuperior, or with lefs felf-denial, in mixed company, left the fubject of conversation to be chosen by others." Preface, p. lxviii.

His attention was awake, even to the mere trifles of life. His domeftic affairs were regulated with an attention to minute circumftances, rarely to be obferved in the household of a philofopher; and the fortune which his admirable acconomy enabled him to amafs (notwithstanding various diminutions that his income fuffered from his liberal and friendly difpofition), was accurately bequeathed to his near relations, in fhares proportioned to the degree which each individual poffeffed of his esteem. He was often heard to exprefs anxiety with refpect 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 fingular how characteriftic of the man, and how fuitable to fuch feelings, this laft fcene actually proved.

"On the 26th November 1799, and in the feventy-first year of his age, he expired, without any convulfion, fhock or ftupor, to announce or retard the approach of death. Being at table, with his ufual fare, fome bread, a few prunes, and a measured quantity of milk, diluted with water, and having the cup in his hand when the laft ftroke of his pulfe was to be given, he had fet it down on his knees, which were joined together, and kept it feady with his hand, in the manner of a perfon perfectly at cafe; and in this attitude expired, without fpilling a drop, and without a writhe in his countenance; as if an experiment had been required to fhew to his friends the facility with which he departed." His fervant opened the door to tell him that fome one had left his name; but, getting no anfwer, stepped about half way towards him, and feeing him fitting in that eafy pofture, fupporting his bafon of milk with one hand, he thought that he had dropped afleep, which he had fometimes feen happen after his meals. He went back, and fhut the door; but before he got down ftairs, fome anxiety, which he could not account for, made him return and look again at his mafter. 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 Fergufon.

to go away; but again returned, and, coming quite clofe to him, he found him without life.' Preface, lxxiv. Ixxv.

Such was the man, of whofe lectures the volumes now before us contain a faithful tranfcript. They are, therefore, a most valuable ac uifition, although we fhould allow them only the merit of a literary curiofity, a relique of the greatest inductive philofopher that has appeared fince the days of Sir Ifaac Newton, and, unfortunately, one of the very few monuments which his modetty 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 difcovery of latent heat, and a much more copious account of the difcovery of fixed air than that which the author publifhed during his life.

The former of thefe difcoveries is, in our opinion, the moft important in its confequences, and the most figual, with regard to difficulty, of any that has been made fince 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 feparated, by a vaft interval, from the previous fleps of our knowledge. By how many infenfible gradations did we arrive at the doctrine of the compofition of water? First, the inflammation of certain vapours was observed; then, the difcovery of fixed air having taught philofophers to examine the properties of certain elaftic fluids, one of thefe was found to differ from the rest in being inflammable. It was afterwards remarked, that this air, when flowly burnt, produced moisture upon a cold body held over the flame: fixed air was, by fome, thought to be produced in the fame procefs: and reafoners, inferred from hence, that the water had been contained in the inflammable air. But others varied the experiment, and burned the air in clofe veffels; moifture was ftill formed, and accurate obfervation fhowed that no new aeriform product refulted from the combuftion. A new fpecies of air having been discovered, much better calculated than common atmospherical air to fupport flame, the combuftion of inflammable air was tried with this new fpecies, and it was found to be extremely rapid. The combuftion being performed in clofe vefiels, the inaccuracy of the experi ment gave rife to various errors; but water was always found to be produced: and fome ingenious men, particularly Mr Watt, reafoning 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 necetary for maintaining the elastic aëriform ftate. This idea was verified by the accurate experiment of Mr Cavendish, in which the quantity of water formed was compared with the quantities of the airs burnt; and the French chemifts added new proofs of

the