Source on Joseph Black

“Black... began a new epoch in Chemistry and Physics, by his fundamental work on Heat, and on the nature of chemical combination; and his name must ever remain associated with those of other illustrious Scotsmen of his day as one who led the way in chemical research and its technical applications.”

“Black's celebrated thesis ...gained for him not merely the degree of Doctor of Medicine, but also brought his name before every "philosopher" in Europe and America as that of a man who had made a discovery of more fundamental influence on the progress of Chemistry than any which had previously been described.”

“In the olden days it was considered quite as marvellous that a gas could be made to occupy a small volume, or that "air" could be produced in quantity from a stone, as that an Arabian "djinn" of enormous size and ferocious mien could issue from a bottle...”

“[I]n the middle of the seventeenth century Robert Boyle had enunciated his famous discovery, "Touching the Spring of the Air"; in which he proved that the greater the pressure to which a gas is exposed the smaller the volume it will occupy. But however great the pressure, Boyle's air remained air.”

“It was Black's discovery of the production of carbonic-acid gas, or, as he named it, "fixed air," from marble, which first directed notice to this possibility of the production of a gas from a solid; and, further, the peculiar property of this gas its power of being fixed was one which completely differentiated it from ordinary air.”

“Stephen Hales... had distilled many substances of vegetable, animal, and mineral origin ; among them he treated many which must have produced impure hydrogen, marsh-gas, carbonic-acid gas, and oxygen; but Hales contented himself with measuring the volume of gases obtained from a known weight of material, without concerning himself as to their properties. And, as the result of many experiments, he concluded that "our atmosphere is a chaos, consisting not only of elastick, but also of unelastick air-particles, which in plenty float in it, as well as the sulphureous, saline, watry, and earthy particles, which are no ways capable of being thrown off into a permanently elastick state, like those particles which constitute true permanent air." This was the current belief as regards the nature of air.”

“[I]t was with the object of discovering a "milder alkali," and bringing it into the service of medicine, that Black began his experiments on magnesia. They are described in... "Experiments upon Magnesia Alba, Quicklime, and some other Alcaline Substances"... his thesis for the... M.D... at Edinburgh in 1754; he had been making the experiments since 1752. The actual thesis was in Latin: "De Humore Acido a Cibis orto, et Magnesia Alba"; the pamphlet was published in the following year.”

“As Dr. Black had never anything for ostentation, he was at all times precisely what the occasion required, and no more. Never did anyone see Dr. Black hurried at one time to recover matter which had been improperly neglected on a former occasion. Everything being done in its proper season and place, he ever seemed to have leisure in store; and he was ready to receive his friend or acquaintance, and to take his part with cheerfulness in any conversation that occurred.”

“As he advanced in years, his countenance continued to preserve that pleasing expression of inward satisfaction, which, by giving ease to the beholder, never fails to please. His manner was perfectly easy and unaffected, and graceful. He was of most easy approach, affable, and readily entered into conversation, whether serious or trivial. His mind being abundantly furnished with matter, his conversation was at all times pertinent and agreeable. He was a stranger to none of the elegant accomplishments of life.”

“During the period in which the theory of phlogiston reached its zenith, four names stand out in bold relief. They are those of Joseph Black (1728–99), Henry Cavendish (1731–1810), Karl Wilhelm Scheele (1742–86), and Joseph Priestley (1733–1804). Of these men the last three were steadfast adherents of the theory, while Black seems to have been indifferent, devoting himself to his researches and placing his own interpretation upon his results.”

“Black was Professor of Chemistry at Glasgow and Edinburgh successively, and although he published only three papers on chemical subjects, these were models of accuracy and logic, and may still be read with profit by the novice—and indeed by the mature chemist. The most important of the three is entitled Experiments upon Magnesia Alba, Quicklime, and some other Alcaline Substances, published in 1756. A modern reprint of it was made by the Alembic Club...”

“In all essentials, Black's explanation is identical with our own, and the careful logic of his procedure makes his monograph conspicuous at once among the multitude of useful researches which were now beginning to bear witness to the new spirit in chemistry.”

“His only other important discovery was that of the bicarbonates, but he is nevertheless correctly regarded as one of the greatest chemists of one of the most fruitful periods of chemistry, and his fame rests upon impregnable foundations.”

“Black's research began in an attempt to produce a milder alkali [for medicinal use] from Epsom salts. ...He commenced by studying the different forms of lime. Limestone, when heated in a fire, became activated, and this quicklime, when placed in water, generated much heat, and was transformed into slaked lime. The limestone was supposed to have absorbed phlogiston from the fire and later to have lost it to the water. Black heated a weighed quantity of marble and found that in the process it lost weight, thus giving the first blow to the phlogiston theory. He next showed that if slaked lime be treated with a mild alkali, such as sodium carbonate, it is changed again to chalk, while the mild alkali becomes caustic alkali.”

“In modern nomenclature the changes are:  {| |- |1. || CaCO3=CaO+CO2. |- |2. || CaO+H2O-=Ca(OH)2. |- |3. || Ca(OH)2+Na2CO3=CaCO3+2NaOH. |}”

“Black realized that when chalk or marble was heated, a gas which he called fixed air was released. He was able to collect the gas, which we know as carbon dioxide, and to study its properties. He was also able to show that carbon dioxide was a normal constituent of the air because quicklime was changed into ordinary chalk, albeit tardily, by exposure to air. This was the first atmospheric gas to be isolated and described. The discovery heralded the dawn of a new era in chemical investigation, and so Black is often given the title-Father of Pneumatic Chemistry.”

“Much of Black's success was due to his accuracy in weighing. The experiments quoted are the first example of a reversible chemical reaction. A certain weight of chalk is taken in experiment 1 and the same weight is recovered at the end of experiment 3. In the words of Sir William Ramsay, "his proof that the change of a complex compound to simpler compounds, and the building up of a complex compound from simpler ones, can be followed successfully by the use of the balance, has had for its consequence the whole development of chemistry." On this score he has been called the Father of Quantitative Chemistry.”