184 



, R. Clausius on the Application of the 



7. I have represented in my former memoir the two principal 

 theorems which hold good for every circular process, by the fol- 

 lowing equations. 



(i) Q-A.W 



(«) /^=-* 



in which the letters have the same signification as they have 

 there, namely — 



A is the equivalent of heat for the unit of work. 



^represents the external work done during the circular process. 



Q signifies the heat communicated to the changeable body dur- 

 ing the circular process, and d Q an element of the same by which 

 a quantity of heat taken from the body is considered as negative 

 communicated heat. The integral of the second equation ex- 

 tends over the whole quantity Q. 



T is a function of the temperature which the variable body 

 has at the moment at which it takes up the element of heat dy } 

 or, should this body have different temperatures in its different 

 parts, of the temperature of the part which takes up dQ. As to 

 the form of the function T, I have shewn in my previous memoir 

 that it is probably nothing else than the temperature itself, when 

 this is estimated from the point which is determined by the re- 

 ciprocal value of the coefficient of expansion of an ideal gas, 

 and which must lie in the neighborhood of —273° C, so that 

 when the temperature estimated from the freezing point is de- 

 noted by we have 



(1) T=27S+t. 

 In future I shall employ the magnitude T always with this sig- 

 nification, and call it briefly the absolute temperature, remark- 

 ing however that the conclusions arrived at do not in their 

 essence depend upon this assumption, but remain valid even if 

 we regard T as a still undetermined function of the temperature. 



Finally, N signifies the equivalent value of all the uncompen- 

 sated changes occurring in the circular process.* 



* A species of uncompensated transformations requires here a special notice. The 

 sources of heat which are to communicate heat to the variable body must have 

 higher temperatures than this last, and conversely those which are to communicate 

 to it negative heat, or to take away heat from it, must have lower temperatures. At 

 every exchange of heat between the variable body and a source of heat, there is an 

 immediate passage of heat from a body of a higher temperature to one of a lower 

 temperature, and herein lies an uncompensated transformation which is so much the 

 greater, the more different the two temperatures are. Whether these uncompensa- 

 ted transformations, in the determination of which not only the changes of condition 

 of the variable body, but also the temperatures of the sources of heat applied come 

 into consideration, are embraced in N or not, depends upon the signification which 

 we attribute to the temperature occurring in equation (n). If we understand by 

 this the temperature of the source of heat belonging to the element dQ, these trans- 

 formations are included in N. If however we understand by it as is above deter- 

 mined, and as it will be understood in this whole memoir, the temperature of the 

 variable body, these transformations are excluded from N. Furthermore a remark 



