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.