548 M. R. Clausius on the Influence of Pressure 



trie tensions, are very different. By plunging two platinum wires 

 into certain portions of the flame, we might even obtain a cur- 

 rent which passes, not from top to bottom, as in the cases here- 

 tofore described, but from bottom to top. On this point I will 

 remain for the present silent, as my intention at the commence- 

 ment was to limit myself to the simplest cases of the phse- 

 nomena. 



LXXVIII. On the Influence of Pressure upon the Freezing of 

 Fluids. By R. Clausius*. 



ly/I R. WILLIAM THOMSON has described an experimental 

 •i-'J- investigation, conducted by himselff, and originating 

 in a theoretic view entertained by his brother, James Thomson. 

 The latter had concluded, from the known principle of Camot, 

 that by an increase of pressure the freezing-point of water must 

 be lowered, which view was completely verified by experiment. 



Some time ago I published a theoretic memoir J, in which 

 the principal part of Camot's law is retained, but altered in 

 one minor particular. This alteration rendered certain of the 

 conclusions heretofore deduced from the principle impossible, 

 while others remained valid ; the latter being those whose cor- 

 rectness or higli probability had been demonstrated by expe- 

 riment. Now as the above conclusion regarding the freezing- 

 point of fluids has also been substantiated experimentally, and 

 thus in a scientific point of view has obtained a greater signifi- 

 cance than one would be inclined at first sight to attribute to so 

 small a difi*erence, I feel myself called upon, in behalf of my 

 theory, to show that my alteration of Carnot^s principle is in no 

 way opposed to this result §. And applying at the same time 

 the original maxim which I have assumed, a new conclusion is 

 arrived at, which, although practically unimportant, on account 

 of the smallness of the numbers wliicli it embraces, deserves 

 nevertheless theoretic expression. 



A lengthened analysis of the subject is not here necessary. 

 The considerations dwelt upon in my former paper regarding 

 the evaporation of a fluid, may be a})plicd almost vei'batim to the 

 freezing of the same. We have only to conceive the vessel im- 

 pervious to heat to be filled partly with a solid body and partly 

 with a fluid one, instead of, as in the former case, partly with a 



* From PoggendorfF's Annalen, vol. Ixxxi. p. 168. 



t Proceedings of the Royal Society of Edinburgh, February 1850; and 

 Phil. Mag., S. '6. vol. xxxvii. p. 123. 



X Phil. Mag. S. 4. vol. ii. pp. 1, 102. 



§ I need hardly mention that I have here no thought of disputing with 

 Mr. Thomson the priority of his ingenious application of the princijde of 

 Camot. 



