William Cullen, Joseph Black 65 



the reputation of academic science in the eighteenth century 

 is retrieved by the splendid record of the Scotch Univer- 

 sities, and notably of Edinburgh. It was indeed a brilliant 

 period in which Black originated quantitative chemistry, 

 Hutton founded the science of geology, Robert Simpson 

 taught mathematics, and John Robison, natural philosophy, 

 while Watt worked out his inventions, and in other branches 

 of knowledge Adam Smith and David Hume added to the 

 fame of their Universities. 



William Cullen (1710-1790), who may be said to be the 

 founder of the Scotch school of chemists, studied at the 

 University of Glasgow, and at the age of nineteen obtained, 

 through the influence of friends, a post as surgeon on a 

 merchant ship sailing to the West Indies. On his return 

 home he became a medical practitioner in his native town, 

 Hamilton, but a small legacy enabled him to spend two 

 years at Edinburgh, in order to pass through a regular 

 course of study. After a period of activity in Glasgow, 

 during which he occupied the Chair of Medicine, and assisted 

 in founding the medical school in that university, he returned 

 to Edinburgh as Professor of Chemistry. Cullen was the 

 discoverer of the lowering of temperature which takes place 

 when a liquid evaporates, or a solid dissolves in a liquid. 

 He also experimented on the heat generated in chemical 

 transformations . 



It was no doubt these researches on heat which directed 

 Joseph Black's attention to that subject. Black (1728- 

 1799) was the son of a Scotch wine merchant living at 

 Bordeaux. He was educated at Belfast, Glasgow and Edin- 

 burgh, studied medicine at the latter University, and 

 presented to it at the age of twenty-six an inaugural disser- 

 tation containing discoveries of fundamental importance to 

 chemistry. Limestone, which forms so important a portion 

 of the earth's surface layers, was at that time considered 

 to be an elementary substance. It was known, of course, 

 that at a high temperature its properties are changed; it 

 becomes quicklime, which gives off a great amount of heat 

 when brought into contact with water. This was explained 

 at the time by supposing that the limestone absorbed, when 

 heated, an imaginary thermal or caustic substance which 



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