102 SCIENTIFIC THOUGHT. 



by the school of which Laplace was the most distin- 

 guished representative, natural philosophers like Black, 1 

 Eumford, and Davy had approached the study of those 

 phenomena where heat and chemical change are the 

 prominent features. The phenomena which they 

 studied experimentally can be comprehended under the 

 head of the disappearance and appearance of heat as 

 measured by the thermometer, or as recognisable 

 directly by our sensation of heat. Black accounted 

 for the disappearance of heat by the doctrine of latent 

 heat, and measured this by the capacity 2 for heat, or 

 the specific heat of different substances. Rumford 

 made exact measurements of the heat generated by 

 friction, and showed that Black's doctrine of latent 

 7. heat did not account for it. Both Black and Rum- 



Black, 



Rumford, f or( j were led to science from the side of practical in- 



and Davy. 



terests. Black, like Young after him, was a physician. 

 Rumford was all through his life occupied with the 



1 Joseph Black (1728-99), one of 156, &c. Black, who as early as 

 the founders of chemistry, and a 1755 had shown that carbonic acid 

 prominent figure in that illustrious gas could disappear as a gas and 

 circle of philosophers who, during become "fixed," showed later 

 the second half of the eighteenth that heat could disappear as tern- 

 century, made the literature and perature and become "latent." 

 science of Scotland renowned over By himself, indeed, the former 

 the whole world, published very important discovery was not inter- 

 little, being mostly known through preted against the then reigning 

 his teaching and his pupils. His phlogistic theory, nor was the latter 

 name is, even to the present day, used to upset the material theory 

 rarely to be found in French books ; of heat. Now, however, both clis- 

 whereas in Germany, mainly owing coveries are corner-stones in the 

 to the historical writings of Herr- history of science, 

 mann Kopp, and quite recently of 2 According to Dr Young ( ' Lee- 

 Prof. E. Mach, his great merit and tures,' new ed., p. 499), the term 

 originality have been fully recog- "capacity" is due to Dr Irvine, 

 nised. See Kopp, 'Geschichte der who, as well as Dr Crawford, was 

 Chemie,' vol. i. p. 226, &c.; 'Die Ent- much influenced by Black's lec- 

 wickelungder Chemie,'1873, pp. 57, tures. These were first published 

 Ac., 88, &c. ; E. Mach, 'Die Prin- in 1802 by Robison, three years 

 cipien der Warmelehre,' 1896, p. after the author's death. 



