Black, Joseph

, one of the most eminent chemical philosophers of the last century, was born in France, on the banks of the Garonne, in 1728. His father, Mr. John Black, was a native of Belfast, in Ireland, but of a Scotch family, which had been some time settled there. Mr. Black resided most commonly at Bourdeaux, where he | carried on the wine trade. He married a daughter of Mr* Robert Gordon of the family of Halhead, in Aberdeenshire, who was also engaged in the same trade at Bourdeaux. Mr. Black was a gentleman of the most amiable manners, candid and liberal in his sentiments, and of no common information. He enjoyed the particular intimacy and friendship of the celebrated president Montesquieu, who most likely acquired his knowledge of the constitution of Britain, for which he was known to have a strong partiality, from the information communicated by Mr. Black. Long before Mr. Black retired from business, his son Joseph was sent to Belfast, that he might have the education of a British subject. He was then twelve years of age, and six years after, in the year 1746, he was sent to continue his education in the university of Glasgow. Being required by his father to make choice of a profession, he preferred that of medicine, as most suited to the general bent of his studies.

It was fortunately at this time that Dr. Cullen had just entered upon his great career, was become conscious of his strength, and saw the great unoccupied field of philosophical chemistry open before him. He quickly succeeded in taking chemistry out of the hands of mere artists, and exhibited it as a liberal science. His pupils became zealous chemists, as well as refined physiologists. Young Black was particularly delighted with the science, and his great bias to the study was soon perceived by Dr. Cullen, who delighted to encourage and assist the efforts of his students. He soon attached Mr. Black to himself so closely, that the latter was considered as his assistant in all his operations, and his experiments were frequently referred to as good authority. Our young philosopher had laid down a very comprehensive plan of study, as appears from his note-books, which are still preserved. In these he wrote down every thing that occurred to him, and they exhibit the first germs and progress of his ideas, till the completion of those great discoveries which produced so complete a revolution in chemical science.

In 1750, he went to Edinburgh to finish his medical studies, and while in that city he lived with his cousingerman, Mr. Russel, professor of natural philosophy in that university. At this time the medical professors entertained different opinions concerning the action of lithontriptic medicine, particularly lime-water, and the students | as usual entered eagerly into the controversy. It seems to have been this circumstance that led Mr. Black to investigate the cause of causticity, a property in which all the litnontriptics then in vogue agreed. At first he suspected that lime, during the burning of it, imbibes something from the fire, which it afterwards communicates to alkalies: this he attempted to separate and collect, but obtained nothing. This led him to the real cause, which he detected about the year 1752, and published soon after, in his inaugural dissertation on magnesia. Limestone he found a compound of lime and fixed air. Heat separates the air and leaves the lime. The common alkalies of commerce, are compounds of the pure alkaline substance and fixed air. Lime abstracts the fixed air from these bodies hence their causticity. This important discovery was detailed at full length in the above dissertation on magnesia and quick lime, published 1755.

At this time Dr. Cullen was removed to Edinburgh, and there being a vacancy in the chemical chair at Glasgow, it was immediately agreed that it could not be bestowed with greater propriety than upon the author of so important a discovery. Accordingly, Dr. Black was appointed professor of anatomy, and lecturer on chemistry in the university of Glasgow, in 1756, but not conceiving himself so well qualified for filling the anatomical chair, he obtained the concurrence of the university to exchange tasks with the professor of medicine. While in Glasgow, therefore, his chief business was delivering lectures on the institutes of medicine. His reputation as a professor increased every year, and he became a favourite practitioner in that large and active city. Indeed, the sweetness of his temper could not fail to make him a welcome visitor in every family. His countenance was no less engaging than his manner was attractive. The ladies regarded themselves as honoured by his attentions, particularly as they were exclusively bestowed on those who evinced a superiority of mental accomplishments or propriety of demeanour, and of grace and elegance of manner. This situation, and the anxious care which he took of his patients, may in some measure account for the little progress made by Dr. Black in that fine career of experimental investigation which he had so auspiciously opened. Yet his inactivity must be lamented as highly injurious to | science it displayed an indolence or carelessness of reputation not altogether to be justified.

But perhaps the other regions of chemistry held out temptations too captivating not to engage his attention. It was between the years 1759 and 1763, that he brought to maturity his speculations concerning heat, which had occupied his attention at intervals, from the very first dawn of his philosophical investigations. His discoveries in this department of science were by far the most important of all that he made, and perhaps indeed the most valuable which appeared during the busy period of the eighteenth century. To enter fully into the nature of his investigations would be improper in this place; but the sum of them all was usually expressed by him in the following propositions.

1. When a solid body is converted into a fluid, there enters into it, and unites with it, a quantity of heat, the presence of which is not indicated by the thermometer, and this combination is the cause of the fluidity which the body assumes. On the other hand, when a fluid body is converted into a solid, a quantity of heat separates from it, the presence of which was not formerly indicated by the thermometer. And this separation is the cause of the solid form which the fluid assumes.

2. When a liquid body is raised to the boiling temperature by the continued and copious application of heat, its particles suddenly attract to themselves a great quantity of heat, and by this combination their mutual relation is so changed, that they no longer attract each other, but are converted into an elastic fluid-like air. On the other hand, when these elastic fluids, either by condensation, or by the application of cold bodies, are reconverted into liquids, they give out a vast quantity of heat, the presence of which was not formerly indicated by the thermometer.

Thus water when converted into ice gives out 140* of heat, and ice when converted into water absorbs 140 of heat, and water when converted into steam absorbs about 1000 of heat without becoming sensibly hotter than 212. Philosophers had been long accustomed to consider the thermometer as the surest method of detecting heat in bodies, yet this instrument gives no indication of the 140* of heat which enter into air when it is converted into water, nor of the 1000 which combine with water when it | is converted into steam. Dr. Black, therefore, said that the heat is concealed (latet) in the water and steam, and he briefly expressed this fact by calling the heat in that case latent heat.

Dr. Black having established this discovery by simple and decisive experiments, drew up an account of the whole investigation, and read it to a literary society which met every Friday in the faculty- room of the college, consisting of the members of the university, and several gentlemen of the city, who had a relish for philosophy and literature. This was done April 23, 1762, as appears by the registers. This doctrine was immediately applied by its author to the explanation of a vast number of natural phenomena, and in his experimental investigations he was greatly assisted by his two celebrated pupils Mr. Watt and Dr. Irvine.

As Dr. Black never published an account of his doctrine of latent heat, though he detailed it every year subsequent to 1762 in his lectures, which were frequented by men of science from all parts of Europe, it became known only through that channel, and this gave an opportunity to others to pilfer it from him piece-meal. Dr. Crawford’s ideas respecting the capacity of bodies for heat, were originally derived from Dr. Black, who first pointed out the method of investigating that subject/

The investigations of Lavoisier and Laplace concerning heat, published many years after, were obviously borrowed from Dr. Black, and indeed consisted in the repetition of the very experiments which he had suggested. Yet these philosophers never mention Dr. Black at all: every thing in their dissertation assumes the air of originality; and, indeed, they appear to have been at great pains to prevent the opinions and discoveries of Dr. Black from being known among their countrymen. But perhaps the most extraordinary procedure was that of Mr. Deluc this philosopher had expressed his admiration of Dr. Black’s theory of latent heat, and had offered to become his editor. Dr. Black, after much entreaty, at last consented, and the proper information was communicated to Mr. Deluc. At last the “Idées sur la Meteorologie” of that philosopher appeared in 1788. But what was the astonishment of Dr. Black and his friends, when they found the doctrine claimed by Deluc as his own, and an expression of | satisfaction at the knowledge which he had acquired of Dr. Black’s coincidence with him in opinion!

Dr. Black continued in the university of Glasgow from 1756 to 1766, much respected as an eminent professor, much employed as an able and most attentive physician, and much beloved as an amiable and accomplished gentleman, and happy in the enjoyment of a small but select society of friends. Often, however, says Dr. Robison, have I seen how oppressive his medical duties were on his spirits, when he saw that all his efforts did not alleviate the sufferings of the distressed. When his dear friend Dr. Dick, professor of natural philosophy, was carried off, Dr. Black’s distress indeed was exceedingly great, particularly as he thought that another mode of treatment might have been more successful.

In 1766 Dr. Cullen was appointed professor of medicine in the university of Edinburgh, and thus a vacancy was made in the chemical chair of that university. Dr. Black was with universal consent appointed his successor. In this new scene his talents were more conspicuous, and more extensively useful. He saw this, and while he could not but be highly gratified by the great concourse of pupils, which the high reputation of the medical school of Edinburgh brought to his lectures, his mind was forcibly impressed by the importance of his duties as a teacher. This had an effect which, perhaps, was on the whole rather unfortunate. He directed his whole attention to his lectures, and his object was to make them so plain that they should be adapted to the capacity of the most illiterate of his hearers. The improvement of the science seems to have been laid aside by him altogether. Never did any man succeed more completely. His pupils were jiot only instructed, but delighted. Many became his. pupils merely in order to be pleased. This contributed greatly to extend the knowledge of chemistry. It became in Edinburgh a fashionable part of the accomplishment of a gentleman.

Perhaps, also, the delicacy of his constitution precluded him from exertion; the slightest cold, the most trifling approach to repletion, immediately affected his breast, occasioned feverishness, and, if continued for two or three days, brought on a spitting of blood. Nothing restored him but relaxation of thought and gentle exercise. The | sedentary life to which study confined him was manifestly hurtful, and he never allowed himself to indulge in any intense thinking without finding these complaints sensibly increased.

So completely trammeled was he in this respect, that, although his friends saw others disingenuous enough to avail themselves of the novelties announced by Dr. Black in his lectures, and therefore repeatedly urged him to publish an account of what he had done; this remained unaccomplished to the last. Dr. Black often began the task, but was so nice in his notions of the manner in which it should be executed, that the pains he took in forming a plan of the work, never failed to affect his health, and oblige him to desist. Indeed, he peculiarly disliked appearing as an author. His inaugural dissertation was the work of duty. His “Experiments on Magnesia, Quicklime, and other alkaline substances,” was necessary to put what he had indicated in his inaugural dissertations on a proper foundation. His “Observations on the more ready Freezing of water that has been boiled,” published in the Philosophical Transactions for 1774, was also called for; and his “Analysis of the Waters of some boiling Springs in Iceland,” made at the request of his friend T. I. Stanley, esq. was read to the royal society of Edinburgh, and published by the council. And these are the only works of his which appeared in print before the publication of his lectures after his death, by professor llobison, in 1803, 2 vols. 4to.

The aspect of Dr. Black was comely and interesting. His countenance exhibited that pleasing expression of inward satisfaction, which, by giving ease to the beholder, never fails to please. His manner was unaffected and graceful. He was affable, and readily entered into conversation, whether serious or trivial. He was a stranger to none of the elegant accomplishments of life. He had a fine musical ear, with a voice which would obey it in the most perfect manner; for he sung and performed on the flute with great taste and feeling, and could sing a plain air at sight, which many instrumental performers cannot do. Without having studied drawing, he had acquired a considerable power of expressing with his pencil, and seemed in this respect to have the talents of a history painter. Figure, indeed, of every kind, attracted his attention. Even a retort, or a crucible, was to his eye an | example of beauty or deformity. He had the strongest claim to the appellation of a man of propriety and correctness. Every thing was done in its proper season, and he ever seemed to have leisure in store. He loved society, and felt himself beloved in it; never did he lose a single friend, except by the stroke of death. His only apprehension was that of a long continued sick bed -less, perhaps, from any selfish feeling, than from the consideration of the trouble and distress which it would occasion to attending friends: and never was this generous wish more completely gratified. On the 26th Nov. 1799, and in the seventy-first year of his age, he expired without any convulsions, shock, or stupor, 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 the pulse was to be given, he set it down on his knees, which were joined together, and kept it steady with his hand, in the manner of a person perfectly at ease; and in this attitude expired, without spilling a drop, and without a writhe in his countenance, as if an experiment had been required to shew 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 seeing him in that easy posture, supporting his bason of milk with one hand, he thought that he had dropt asleep, which sometimes happened after his meals. He went back and shut the door; but before he went down stairs, some anxiety, which he could not account for, made him return again, and look at his master. Even then he was satisfied after coming pretty near him, and turned to go away but returning again, and coming up close to him, he found him without life.

To this sketch, abridged from professor Robison’s life for the Literary Journal, we have only to add, that Fourcroy, the eminent French chemist, used to call Dr. Black, the illustrious Nestor of the chemical revolution, and indeed, in every part of Europe, where chemistry has been studied, Dr. Black was named with peculiar veneration. 1

1

Life ubi supra. See also Bibliotheque Britannique, vol. XXVIII.

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