308 Notices respecting New Books. 
stable equilibrium, Chapter VII. with pure bodies and the laws of 
combination, Chapter VIIL. with chemical potential, and Chapter IX. 
with the phase rule. 
The writing of this volume must have cost the author an immense 
amount of thought and trouble, but it isalso amply evident that it 
has been a labour of love, and the style in which the book is 
written cannot fail to communicate to the reader some of the 
author’s own enthusiasm and passionate devotion to truth. 
Treatise on Thermodynamics. By Dr. Max Puancx, Professor of 
Theoretical Physics in the Unwersity of Berlin. Translated, with 
the Author’s sanction, by Alexander Ogg, M.A., B.Sc., Ph.D. 
Longmans, Green & Co. 1903. Pp. xii+272. 
THERMODYNAMIC literature will be considerably enriched by the 
addition to it of Professor Planck’s profound and original treatise. 
There are few subjects in the whole range of physical science 
which require more careful handling than thermodynamics, nor is 
there any in which slipshod and careless methods are more pro- 
ductive of mischief or more conducive to the formation of habits of 
mental dishonesty. Any treatise, therefore, which helps the earnest 
student towards a clearer understanding of this difficult subject by 
a thorough discussion of all its diffiiculties—many of which would 
probably escape his notice unless specially pointed out—is to be 
warmly welcomed. The present treatise is intended not for the 
beginner, but for the advanced student who has already mastered 
the foundations of thermodynamics, and who is in a position to 
take a step upwards by giving his attention to that wider and more 
general mode of treatment which is so characteristic of thermo- 
dynamics. 
To the average mind the study of concrete physical problems is 
always much easier than that of broad general principles applicable 
to a wide range of physical phenomena. As the generality of the 
treatment increases, so does the mental effort required to follow 
it. Few students, for example, acquire a really clear notion of the 
full significance of the conservation of energy until they have 
given careful study to a large number of problems which furnish 
illustrations of it, Similarly, few students are capable of grasping 
the full generality and far-reaching importance of the second law 
of thermodynamics until their minds have to some extent become 
familiarised with thermodynamical ideas by an elementary study 
of the thermodynamics of a perfect gas, based on the notions of 
the kinetic theory. Such a study probably forms the best intro- 
duction to the subject, and for this reason has become established 
as the standard method of dealing with it. But unless the student 
subsequently enlarges his ideas by a more careful study of general 
thermodynamical principles, his conception of thermodynamies will 
be very limited indeed. It is not unusual, for example, to find 
that many students who have passed through an elementary course 
acquire the notion that the second law is something which applies 
to gaseous bodies only—nay, in some cases that it only applies to 
a perfect gas—and that therefore its range is extremely limited. 

