RELATION BETWEEN HEAT AND WORK. 327 



it is none the less my own, and I do not hesitate to assert my 

 right of priority. 



In order to ensure what had been thus discovered against 

 casualties, I put together the most important points in a short 

 paper which I sent in the spring of 1842 to Liebig, with a 

 request that he would insert it in the Annalen der Chemie und 

 Pharmacie, in the forty-second volume of which, page 233, it 

 may be found under the title " Bemerkungen iiber die Krafte 

 der unbelebten Natur." 



It was a fortunate circumstance for me that the reception 

 given to my unpretending work by this man, gifted with so 

 deep an insight, at once secured for it an entrance into one of 

 the first scientific organs, and I seize this opportunity of pub- 

 licly testifying to the great naturalist my gratitude and my 

 esteem. 



Liebig himself, however, had about the same time already 

 pointed out, in more general but ' still unmistakable terms, the 

 connection subsisting between heat and work. In particular, 

 he asserts that the heat produced mechanically by a steam- 

 engine is to be attributed solely to the effect of combustion, 

 which can never receive any increase through the fact of its 

 producing mechanical effects, and, through these, again devel- 

 oping heat. 



From these, and from similar expressions of other scien- 

 tific men, we may infer that science has recently entered upon 

 a direction in which the existence of the mechanical equiva- 

 lent of heat could not in any case have remained longer un- 

 perceived. 



In the paper to which reference has been made, the nat- 

 "ural law with which we are now concerned is referred back 

 to a few fundamental conceptions of the human mind. The 

 proposition that a magnitude, which does not spring from 

 nothing, cannot be annihilated, is so simple and clear that no 

 valid argument can be urged against its truth, any more than 

 against an axiom of geometry ; and until the contrary is 



