Joseph Black was one of the founders of modern chemistry, and the ten years he spent as a professor at the University of Glasgow were among the most consequential any scientist has spent anywhere. There he arrived at the concept of latent heat — and there he befriended, taught and bankrolled a young instrument maker named James Watt, whose separate condenser, born of Black’s science, would power the Industrial Revolution. Born in France, made in Scotland, Black is claimed by Glasgow with good reason: the pivotal decade was hers.
Fixed Air
He was born on 16 April 1728 in Bordeaux, one of a dozen children of a Belfast-Irish wine merchant and his Aberdeenshire wife. Schooled in Belfast, he came to the University of Glasgow in 1746 to study, falling under the influence of the chemist William Cullen, and completed his medical training at Edinburgh. His doctoral work on magnesia alba yielded a discovery of the first rank: a gas he named ‘fixed air’ — carbon dioxide — which he showed to be denser than ordinary air, incapable of supporting flame or life, and a product of breathing and fermentation. In proving that air was not a single element but a mixture of distinct gases, and in measuring his reactions with meticulous use of the balance, Black helped launch the quantitative chemistry that Lavoisier would complete a generation later.
The Glasgow Chair
In 1756 Cullen moved to Edinburgh, and Black, at twenty-eight, succeeded his old teacher as Professor of Anatomy and Chemistry at Glasgow, soon also holding a chair in medicine. He proved a spellbinding lecturer, his classes famous for their live experimental demonstrations, and it was here, freed to follow his curiosity, that he turned from gases to heat. Why, he asked, does ice not melt the instant it warms past freezing, nor water boil away the instant it reaches the boil? The answer was a quiet revolution in physics.
Latent Heat and James Watt
Black showed that a great quantity of heat is absorbed, without any rise in temperature, when a solid melts or a liquid boils — heat that lies concealed, or ‘latent’, in the changed state, and is released again when it reverses. He distinguished for the first time between the quantity of heat and its intensity, or temperature, and invented the means to measure it. The idea had a listener close at hand. James Watt, then the University’s mathematical instrument maker, had a workshop within the college, and the two became firm friends; Black’s understanding of latent heat illuminated exactly why the Newcomen engine wasted so much of its steam, and helped Watt toward the separate condenser of 1765. Black did more than inspire — he repeatedly lent Watt money to keep his experiments alive. Among Black’s Glasgow students, too, was the young Charles Macintosh, the future inventor of the waterproof coat.
The Great Teacher
In 1766 Black left Glasgow to take the chemistry chair at Edinburgh, again succeeding Cullen, and there he largely gave up research to devote himself to teaching, drawing huge audiences from across Europe and America for more than thirty years. A quiet, precise, much-loved figure of the Scottish Enlightenment — a friend of Hume, Adam Smith and James Hutton — he never married, and died in Edinburgh on 6 December 1799, reportedly slipping away calmly in his chair with a cup of milk in his hand. The chemistry buildings of both Glasgow and Edinburgh universities bear his name.
His page belongs in this chapter beside James Watt’s, for the two stories are one: the professor who conceived of hidden heat, and the instrument maker who built an engine on it — a Glasgow friendship that lit the furnace of the modern world.
The Glasgow connection
Black’s Glasgow is the old University: the college on the High Street where he studied under Cullen, held the chair of chemistry and medicine for ten years, first spoke of latent heat, and shared a workshop-side friendship with James Watt — a legacy the modern university keeps in the Joseph Black building that carries his name.
People also ask
Who was Joseph Black?
One of the founders of modern chemistry, and a professor at the University of Glasgow — the man who discovered carbon dioxide and the concept of latent heat, and whose science helped set his friend James Watt on the road to the steam engine.
What did Joseph Black discover?
Two things of the first importance: ‘fixed air’ — carbon dioxide — which he showed to be a distinct gas produced by breathing and burning; and latent heat, the hidden heat involved when matter changes state. He was also a pioneer of careful, quantitative chemistry.
What is latent heat?
The large amount of heat that is absorbed or released when a substance changes state — melting or boiling — without any change in its temperature. Black was the first to identify and measure it, explaining why ice does not melt, nor water boil away, all at once.
What was Joseph Black’s connection to James Watt?
They were close friends and collaborators at the University of Glasgow, where James Watt was the instrument maker. Black’s understanding of latent heat illuminated why the old steam engines wasted so much heat, and helped Watt towards his separate condenser — and Black repeatedly lent him money to keep his experiments alive.
Was Joseph Black from Glasgow?
No — he was born in Bordeaux, in France, in 1728, to a family in the wine trade. But his defining decade was spent as a professor at Glasgow, where he made his discoveries and formed his friendship with Watt, which is why the city claims him.
When did Joseph Black die?
He died in Edinburgh — where he had moved to a second professorship — on 6 December 1799, aged 71, reportedly slipping away calmly in his chair with a cup of milk in his hand.