ON THE PHYSICAL VIEW OF NATURE. 



103 



practical application of scientific knowledge. Black's 

 experiments and measurements contributed largely to 

 fix the difference between temperature and quantity 

 of heat ; he demonstrated clearly that heat may 

 disappear in the form of temperature and exist 

 as latent heat, that is, heat not discoverable by 

 the thermometer. He, however, adhered to the view 

 that heat was a material substance, which, though 

 it might become latent, did not disappear as such. 

 Rumford 1 was the first who definitely went a step further 

 and suggested the convertibility of heat and mechanical 

 work. It was not the disappearance of heat but its 

 appearance when mechanical work was performed which 

 attracted his attention. After eliminating all the 

 sources from which the heat produced during the bor- 

 ing of cannon could have been derived, he comes to the 

 conclusion that " it appears to be extremely difficult, 

 if not quite impossible, to form any distinct idea of 

 anything capable of being excited and communicated 

 in the manner the heat was excited and communicated 

 in those experiments, except it be motion." . Davy, 

 who, like Black, approached science in the interests of 

 the medical man, comes to the conclusion in his first 

 published papers, from experiments on the generation 



1 Count Rumford's "Inquiry con- 

 cerning the Source of the Heat 

 which is excited by Friction" was 

 published in a later edition of his 

 'Essays.' The experiments with 

 the boring of cannon were carried 

 on at Munich in 1796 and 1797 ; 

 the substance of the essay was 

 read before the Royal Society in 

 January 1798. The 'Essays' were 



republished in America and trans- 

 lated into several foreign lan- 

 guages. See Rumford's ' Works,' 

 London, 1876, vol. i. p. 482, 

 and vol. ii. p. 471. In 1804 

 Count Rumford published, in his 

 ' Me"moires sur la Chaleur ' (Paris, 

 an. 13), a "Historical Review of 

 the Various Experiments on Heat " 

 ('Works,' vol. iii. pp. 138-240). 



