THE 

 LONDON, EDINBURGH, and DUBLIN 



PHILOSOPHICAL MAGAZINE 



AND 



JOURNAL OF SCIENCE. 



[FOURTH SERIES.] 



AUGUST 1862. 



XIII. On the Application of the Theorem of the Equivalence of 

 Transformations to the Internal Work of a mass of Matter. By 

 Professor R. Clausius*. 



IN a memoir published in the year 1854f, wherein I sought 

 to simplify to some extent the form of the developments I 

 had previously published, I deduced, from my fundamental pro- 

 position that heat cannot of itself pass from a colder into a wanner 

 body, a principle which is closely allied to, but does not entirely 

 coincide with, the one first deduced by S. Carnot from considera- 

 tions of a different class, based upon the older views of the nature 

 of heat. It has reference to the circumstances under which work 

 can be transformed into heat, and, conversely, heat converted 

 into work ; and I have called it the Principle of the Equivalence of 

 Transformations. I did not, however, there communicate the 

 entire proposition in the general form in which I had deduced it, 

 but confined myself on that occasion to the publication of a part 

 which can be treated separately from the rest, and is capable of 

 more strict proof. 



In general, when a body changes its state, work is performed 

 externally and internally at the same time, — the external work 

 having reference to the forces which extraneous bodies exert 

 upon the body under consideration, and the internal work to the 

 forces exerted by the constituent molecules of the body in ques- 

 tion upon each other. The internal work is for the most part so 

 little known, and connected with another equally unknown quan- 



* Translated from the Mittheilunyen der Naturforschenden Gesellschaft 

 in Zurich, vol. vii. p. 48, having been communicated to the Society on the 

 2/th of January, 1862. 



t " On a modified form of the second Fundamental Theorem in the 

 Mechanical Theory of Heat" (Phil. Mag. S. 4. vol. xii. p. 81; Pogg. 

 Ann. vol. xchi. p. 481). 



Phil. Mag. S. 4. Vol. 24. No. 159. Aug. 1862. G 



