COUNT RUMFORD 171 



everything that he undertook, and always hitting the essence 

 of the matter without pedantry. Among the numerous and 

 manifold activities of his varied life, only one, relating to 

 science, concerns us here, namely his endeavours to discover 

 the nature of heat; his other services to science can only be 

 mentioned shortly, or simply referred to. 



The famous experiment carried out by Count Rumford 

 in the munition workshop at Munich^ started from the exist- 

 ing knowledge of heat, according to which it appeared as an 

 extremely mysterious something, the amount of which, it is 

 true, could be measured with certainty since Black's time; 

 the addition of it in many chemical transformations, 

 and also in the processes of fusion and evaporation of sub- 

 stances, was known to be necessary, but on the other hand 

 it failed to affect the balance. It was thus possible to 

 imagine it as a weightless substance - this was the generally 

 accepted idea, and Lavoisier had introduced the term 

 'caloric' for this substance - and hence of the same 

 nature as the other forms of matter which chemistry 

 had discovered in ever increasing variety. They all had the 

 feature in common of being fundamental substances, which 

 proved to be unchanged in amount, although they might 

 appear to vanish, together with their properties, in the 

 course of chemical combinations. In like manner, heat 

 appears to vanish when ice is turned into water, but reap- 

 pears again when the water freezes to ice, while certain 

 chemical processes, such as combustion, do not require 

 heat, but produce it. But this idea of heat necessarily led 

 to difficulties in the case of a common phenomenon, namely 

 the development of heat by friction. For here heat appears 

 without our being able to find out whence it has come, or 

 where afterwards a deficiency in it is discoverable. This 

 fact struck Count Rumford when he noticed, in the boring of 



^ Published in 1798 in the Philosophical Transactions of the Royal 

 Society. 



