University Of Edinburgh Faculty

"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."

"I do not imagine that Mr. Black's researches at this time (or perhaps at any time) have been keen or pertinacious. This could not accord with the native gentleness of his mind; but his conceptions being distinct, and his judgment sound, his progress in scientific research, if slow, was steady, and his acquisitions were solid. Perhaps this moderation and sobriety of thought was his happiest disposition, and the most conducive to his improvement."

"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 s, 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 [for medicinal use] from Epsom salts. ...He commenced by studying the different forms of lime. , 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 , it is changed again to chalk, while the mild alkali becomes caustic alkali."

"In modern nomenclature the changes are:"

"Black realized that when or was heated, a gas which he called fixed air was released. He was able to collect the gas, which we know as , 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."

"Your happiness on the contrary is quite secure because you place it entirely in making others happy and doing those things to the utmost of your power which you can afterwards reflect upon with satisfaction. I must own your letter had that effect upon me that it made me apply to my work with double eagerness and alacrity with the hopes of being some time what you are at present."

"Others in the pursuits after happiness or pleasure must commonly seek those sources of it which they cannot enjoy without some inconvenience to the rest of their fellow creatures; hence they have their imaginary happiness so much soured by Envy, Jealousy, or self-disapprobation that they find themselves dissappointed."

"Most Honrd Sir Your most affectionate letter of the 8th Aprill shews you in such a light as must warm the heart of a son with the highest degree of gratitude and affection."

"I have now studied the Theory of medicine & have likewise been taught every thing upon the Practice which can be learned in a College. I have also seen some real Practice & have even practised a little myself. But all this is not enough."

"In my last letter to you I proposed to go immediately to London to spend some time in the Hospitals there. I am now advised to put that off and remain here yet a while longer; & I must own the reasons for it are very strong quite unanswerable by me unless you disapprove of them. The following are the chief of them."

"I am not yet installed into the order of the great wig, but have gone through all the examinations, & nothing is wanting but the ceremony, that has been put off by the Processors to wait for some others that are to be promoted along with me 6 days hence."

"In the early part of my chymical studies, the author whose works made the most agreeable impression on my mind was Markgraaf of Berlin; he contrived and executed his experiments with so much chymical skill that they were uncommonly instructive and satisfactory; and he described them with so much modesty and simplicity, avoiding entirely the parade of erudition and self-importance, with which many other authors encumber their works, that I was quite charmed... and said to Dr. Cullen I would rather be the author of Markgraaf's Essays than of all the Chymical works in the library. The celebrated Reaumur's method of writing appeared to me also uncommonly pleasing. After 3 years spent with Dr. Cullen, I came to Edinburgh to finish my education in medicine. Here I attended the lectures of Dr. Munro, senr. and the other medical Professors, until the summer of the year 1754, when I received the degree of Doctor of Medicine, and printed my inaugural Dissertation De Humere Acido a Cibis Orto et Magnesia Alba."