It appears from an anecdote related on good authority, (see Edinburgh Encyclopædia, article, Dr. Black) that so early as 1766, when the low specific gravity of hydrogen as discovered by Mr. Cavendish had been announced, the idea of employing it for balloons occurred to Dr. Black; and that he actually exhibited a small one, to the extreme astonishment of a party of friends. It was not till 1782 Montgolfier claimed the merit of originating this idea.
Dr. Black never enjoyed very robust health, but by great care and attention he managed to the best advantage a constitution naturally delicate, pursuing, especially towards the latter part of his life, an extremely regular and abstemious mode of living. About 1793 his strength began to fail. In 1796 he became unequal to the sole discharge of his duties as a lecturer, and employed an assistant. In the following year he was compelled to relinquish lecturing altogether. Though in great weakness, he was able by unremitting precautions to preserve a considerable share of general health. He had always expressed a hope that he might be spared the distress of a long illness; and, in accordance with this wish, while sitting at table partaking of his usual simple fare, he expired November 26, 1799, in so tranquil a manner, that a cup of milk which he had placed on his knee remained unspilt; and it was some time before his servant perceived that life was extinct.
The cast and character of Dr. Black’s mind is illustrated by the whole nature and course of his labours and investigations. Methodical precision and originality of thought were the qualities which pre-eminently distinguished him. In framing general conclusions he was peculiarly cautious and exact. It is clear that he possessed abilities which might have placed him much higher in the rank of original discoverers, had not an unfortunate backwardness, perhaps the result of natural timidity or indolence, perhaps of weak health and incessant employment, withheld him from pushing his researches to a greater extent, and even from asserting his just claims to what he had done, which was in some instances wrongfully appropriated by others. Some charges of this nature have been brought against Lavoisier, in reference to the discovery of the nature of alkalies; but in his writings Lavoisier certainly does ample justice to Black.
In all the best and most substantial qualifications of a teacher and lecturer, he has seldom been surpassed. His method was luminous and natural; his style unadorned, but beautifully perspicuous; his experimental illustrations completely satisfactory and convincing, yet always of the simplest possible kind. He manifested a great dislike to any unnecessary parade of apparatus, and the exhibition of showy and striking, but useless phenomena. He aimed not at display and popular fame, but to arrive at the best means of interesting, instructing, and enlightening his pupils. He led them by his own example pre-eminently to value accuracy in the establishment of facts, caution in deducing general conclusions, and a resolute adherence to the results derived from experiment and induction.
Dr. Black’s moral and social character was exactly such as harmonized with his mental endowments. He was moderate in his desires, temperate in his enjoyments, benevolent and warm in his affections. He manifested a strong love of order, propriety, and decorum, and a total absence of jealousy against scientific rivals, or envy of their fame. His disposition was at once serious and cheerful; and he was distinguished by a happy equanimity of temper. He was sometimes accused of penuriousness: but the charge is wholly denied by his relative, Dr. Ferguson; and his intimate friend, Professor Robison, has related many instances of his conduct totally incompatible with such a disposition. In person he was rather above the middle height; of a slender figure, with a mild and engaging countenance.
After Dr. Black’s death his manuscript lectures were revised and published by Professor Robison, in two quarto volumes, in 1803. The first and most important portion of the work is devoted to the subject of heat; and contains the development of the author’s original researches to which we have referred. The simplicity of style, the admirable taste and propriety of language, and the perspicuous and luminous method of illustration, cannot be too highly praised. With respect to the other portion, embracing the details of chemistry properly so called, though the same commendation as to the manner must be bestowed, the matter, which was not less excellent for the time at which the lectures were delivered, was yet, at the period of the publication, necessarily much behind the advance of discovery.
Engraved by J. Posselwhite.
LORD BACON.
From a Print by J. Houbraken 1738.
Under the Superintendence of the Society for the Diffusion of Useful Knowledge.
London, Published by Charles Knight & Co. Ludgate Street.
