Joseph Black FRSE FRCS (16 April 1728 – 6 December 1799) was a Scottish  physician, known for his discoveries of latent heat, specific heat, and carbon  dioxide. He was professor of Medicine at University of Glasgow (where he also  served as lecturer in Chemistry). James Watt, who was appointed as philosophical  instrument maker at the same university (1756), became involved in Black's works  and conducted experiments on steam with Black. The chemistry buildings at both  the University of Edinburgh and the University of Glasgow are named after  Black.
 Black was born in Bordeaux, France, where his father, who was from Belfast,  Ireland, was engaged in the wine trade. His mother was from Aberdeenshire,  Scotland, and her family was also in the wine business. Joseph had twelve  brothers and sisters. He entered the University of Glasgow when he was eighteen  years old, and four years later he went to Edinburgh to further his medical  studiesIn about 1750, Joseph Black developed the analytical balance based on a  light-weight beam balanced on a wedge-shaped fulcrum. Each arm carried a pan on  which the sample or standard weights was placed. 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.
 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. The latent heat of water is large  compared with many other liquids, so giving impetus to James Watt's successful  attempts to improve the efficiency of the steam engine invented by Thomas  Newcomen. Watt added a separate condenser, and kept the cylinder at the  temperature of steam (by enclosing it in a steam-filled jacket) so saving a  considerable amount of energy in avoiding the reheating of the cylinder at every  cycle of the engine
 Black also explored the properties of a gas produced in various reactions.  He found that limestone (calcium carbonate) could be heated or treated with  acids to yield a gas he called "fixed air." He observed that the 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.
 In 1757 or 1758 Black became a friend of James Watt, who first began his  studies on steam power at Glasgow University in 1761. He provided significant  financing and other support for Watt's early research on the steam engine. Black  also was a member of the Poker Club and associated with David Hume, Adam Smith,  and the literati of the Scottish Enlightenment. Black never married. He died in  Edinburgh at the age of 71, and is buried there in Greyfriars Kirkyard.
 John Fothergill FRS (8 March 1712 – 26 December 1780) was an English  physician, plant collector, philanthropist and Quaker.Fothergill was born of at  Carr End, near Bainbridge in Yorkshire, the son of John Fothergill (1676–1745),  a Quaker preacher and farmer, and his first wife, Margaret Hough (1677–1719).  After studying at Sedbergh School, Fothergill was apprenticed to an apothecary.  He later took the degree of M.D. at Edinburgh, in 1736, followed by further  studies at St Thomas' Hospital, London. After visiting continental Europe in  1740, he settled in London, where he gained an extensive practice. For example,  during the epidemics of influenza in 1775 and 1776 he is said to have had sixty  patients daily.
 In 1745, he gave a brief lecture to the Royal Society of London, citing the  work of a Scottish physician, William Tossach, which is the first known lecture  on the practice of mouth-to-mouth ventilation.
 Fothergill's pamphlet, Account of the Sore Throat attended with Ulcers  (1748), contains one of the first descriptions of diphtheria in English, and was  translated into several languages. His rejection of ineffective traditional  therapies for this disease saved many lives
 In his leisure, John Fothergill made a study of conchology and botany. At  Upton, near Stratford, he had an extensive botanical garden where he grew many  rare plants obtained from various parts of the world (now West Ham Park).
 He was elected a Fellow of the Royal Society in 1763.
 He was the patron of Sydney Parkinson, the South Sea voyager, and also of  William Bartram, the American botanist.
 A translation of the Bible, known as the Quaker Bible (1764 sq.) by Anthony  Purver, a Quaker, was made and printed at his expense.
 He founded Ackworth School, Pontefract, Yorkshire in 1779.
 John Fothergill died in London aged 68 on 26 December 1780.
  
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