RUDOLF JULIUS EMANUEL CLAUSIUS. 461 



and that for any reversible infinitesimal change 



dQy, = td Z, 



where Z is another function of the state of the body, which he 

 called the disgregation, and regarded as determined by the positions 

 of the elementary parts of the body without reference to their veloci- 

 ties. In this respect it differed from the entropy. An immediate 

 consequence of these relations is that for any reversible cyclic process 



r- 



t ="' 



and therefore that H, the molecular vis viva of the body, must be a 

 function of the temperature alone. This important result was ex- 

 pressed by Clausius in the following words : " Die Menge der in 

 einem Korper wirklich vorhandenen Warme ist nur von seiner 

 Temperatur und nicht von der Anordnung seiner Bestandtheile 

 abhiingig." 



To return to the equation 



d Q^ = t d Z. 



This expresses that heat tends to increase the disgregation, and that 

 the intensity of this tendency is proportional to the absolute tempera- 

 ture. In the words of Clausius : " Die mechanische Arbeit, welche 

 die Warme bei irgend einer Anordnungsiinderung eines Korpers thun 

 kann, ist proportional der absoluten Temperatur, bei welcher die Aen- 

 derung geschieht." 



Such in brief and in part were the views advanced by Clausius in 

 1862, in his memoir, " Ueber die Anwendung des Satzes von der 

 Aequivalenz der Verwandlungen auf die innere Arbeit." * Although 

 they were advanced rather as a hypothesis than as anything for 

 which he could give a formal proof, he seems to have little doubt of 

 their correctness, and his confidence seems to have increased with the 

 course of time. 



The substantial correctness of these views cannot now be called in 

 question. The researches especially of Maxwell and Boltzmann have 

 shown that the molecular vis viva is proportional to the absolute 

 temperature, and Boltzmann has even been able to determine the 

 precise nature of the functions which Clausius called entropy and 

 disgregation. t But the anticipation, to a certain extent, at so early a 



* Pogg. Ann., vol. cxvi. p. 73. See also vol. cxxvii. p. 477 (1866). 

 t Sitzungsberichte Wien. Akad., vol. Ixiii. p. 728 (1871). 



