THE 

 LONDON, EDINBURGH, and DUBLIN 



PHILOSOPHICAL MAGAZINE 



AND 



JOURNAL OF SCIENCE. 



[FOURTH SERIES.] 



JULY 1866. 



I. On the Determination of the Energy and Entropy of a Body, 

 By Professor R. Clausius*. 



IN the second Number for this year of the Zeitschrift fur Ma- 

 thematik und Physik there is a paper by Bauschinger, chiefly 



relating to the integral I -^ , which occurs in the second funda- 

 mental theorem of the mechanical theory of heat, where dQ 

 denotes an element of the quantity of heat which a body takes 

 up in the course of any reversible change of condition, and T 

 the absolute temperature of the body at the moment of absorb- 

 ing this element of heat. Bauschinger developes an expression 

 which represents the value of the integral for finite changes of 

 condition under certain simplifying circumstances, and which, 

 for the case where the final condition is the same as the initial 

 condition, and the body accordingly goes through a circular pro- 

 cess, becomes equal to nothing. In consequence of this last 

 circumstance, Bauschinger supposes that the equation he has 

 developed expresses a general principle, which includes, as a 

 special case, my principle of the equivalence of transformations 

 in circular processes. 



I cannot say that I agree with this view of the import of his 

 developments. 



In the equation 



j¥=°> 



which I established for reversible circular processes, there is 



* Translated from the Zeitschrift fur Mathematik und Physik, vol. xi. 

 part 1, p. 31. 



Phil. Mag. S 4. Vol. 32. No. 213. July 1866. B 



