Person NameBlack; Joseph (1728-1799); Professor; chemist; physician
Epithetchemist; physician
HistoryBlack was born in Bordeaux where his father was engaged in the wine trade. He entered the University of Glasgow when he was eighteen years old, and four years later he went to Edinburgh to further his medical studies.

In about 1750, Joseph Black developed the analytical balance based on a light-weight beam balanced on a wedge-shaped fulcrum. It far exceeded the accuracy of any other balance of the time and became an important scientific instrument in most chemistry laboratories. In 1757, he was appointed Regius Professor of the Practice of Medicine at the University of Glasgow. At the same time he became a friend of James Watt, who first began his studies on steam power at Glasgow University in 1761. Black provided significant financing for Watt's early research on the steam engine.

In 1761 Black deduced that the application of heat to ice at its melting point does not cause a rise in temperature of the ice/water mixture, but rather an increase in the amount of water in the mixture. Additionally, Black observed that the application of heat to boiling water does not result in a rise in temperature of a water/steam mixture, but rather an increase in the amount of steam. From these observations, he concluded that the heat applied must have combined with the ice particles and boiling water and become latent. The theory of latent heat marks the beginning of thermodynamics. Black's theory of latent heat was one of his more important scientific contributions, and one on which his scientific fame chiefly rests. He also showed that different substances have different specific heats.

This all proved important not only in the development of abstract science but in the development of the steam engine, giving impetus to James Watt's successful attempts to improve the efficiency of the steam engine invented by Thomas Newcomen.

Black also explored the properties of a gas produced in various reactions. He found that limestone (calcium carbonate) could be treated with acids to yield a gas he called "fixed air." He observed that fixed air was denser than air and did not support either flame or animal life. Black also found that when bubbled through an aqueous solution of lime (calcium hydroxide), it would precipitate calcium carbonate. He used this phenomenon to illustrate that carbon dioxide is produced by animal respiration and microbial fermentation.

Black never married and died in Edinburgh at the age of 71. He is buried there in Greyfriars Kirkyard.

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