

Notices respecting New Books. 307 



more probably true for the same substance changed only as 

 to temperature and pressure. In other words, the relation 

 of melting-point to pressure is presumably linear. In my 

 work on the continuity of solid and liquid * these relations 

 are corroborated for naphthalene within an interval of 2000 

 atmospheres. 



XXIX. Notices respecting New Books. 



Treatise on Thermodynamics. By Peter Alexander, M.A. 

 London : Longmans, Green, and Co. 1892. 



Tj^ROM the preface it appears that this book is ambitious : it 

 -*- claims to have elevated the science of Thermodynamics into 

 an organic unity from being a mere collection of detached propo- 

 sitions, to exhibit the thermodynamic relations as the outcome of 

 physical, as opposed to mathematical, considerations, to have 

 cleared away the fog that has enwrapped the subject of irreversi- 

 bility, and, by an enlarged definition of entropy, to have opened 

 up a mode of dealing with this subject, and, finally, to have 

 dissipated the haziness that has overlain the subjects of Motivity 

 and Dissipation of Energy. 



The idea is to be deprecated, however, that, as hitherto treated, 

 the science of Thermodynamics has consisted of anymore detached 

 propositions than the two, representing the two laws, which are 

 the necessary basis of this as of every other treatise on the sub- 

 ject, viz. that of the conservation of energy and that of the perfec- 

 tion of a reversible engine or its equivalent, together with their 

 consequences ; and indeed a set of relations, which are the expres- 

 sions in different forms of the same fact and which are all deducible 

 from each other by simple transformations, does not constitute 

 different but identical propositions. What the author has really 

 done is to express the two laws, i. e. practically the values of the 

 dynamical equivalent and of Carnot's function, in a manner even 

 more general than that worked out (though not otherwise employed) 

 by Clausius, viz. in terms of two general variables with any scale 

 of temperature 'whatever, and then from these expressions to deduce 

 particular thermodynamic relations by the substitution of particular 

 variables : and it is these relations, which are necessarily identical, 

 that constitute the " detached propositions " above mentioned. 



Even if this method does not really tend to promote the organic 

 unity of the science, it has without doubt its advantages and, by 

 reason of its generality, should find plane in some form or other 

 in every formal text-book : it is certainly convenient if only as a 

 simple mode of demonstrating certain identities and even of bringing 

 to light identities, unimportant enough it may be, that might 

 otherwise escape recognition. At the same time it is unlikely that 

 general resort will be made to it for obtaining the really important 



* Am. Jjoura. xlii. p. 144 (1891), 



