[ 100G ] 



CXIV. Notices respecting uS r ew Books. 



Introduction to Physical Chemistry. By Professor Harry C. Jones. 



New York : The MacMillan Company, 1910. $1.60 net. 

 r PHE vitality of Physical Chemistry is exhibited as much in the 

 -*- number of text-books \\ ritten upon it as in the rapid progress 

 which is being made in this branch of science itself. The appear- 

 ance of still another will doubtless be justified, and its merits are 

 such that it will probably prove a strong rival to those alreadv in 

 the field. 



Let it b9 said, in the first place, that the style in which the 

 book is written is an excellent one. The statements are easy to 

 follow; and considering that only a rudimentary account of the 

 subject-matter is intended, they are as complete as could be 

 I. A doubl will arise in the minds of some readers whether 

 it is well to attempt to give something about everything rather 

 than to concentrate attention in a more thorough manner upon a 

 few things. The writer follows the former course ; the result is 

 a wry complete elementary resume of the principal facts, while 

 cplanations of these tacts are given in a more imperfect way 

 when given at all. Professor Jones is obviously writing for the 

 man who has no mathematical knowledge, and difficulties fre- 

 quently occur under these circumstances in giving a satisfactory 

 explanation. We think that he succeeds on the whole; but there 

 are many places where considerable improvement could be effected. 

 A notable case occurs on ]). 20, where he attempts to (but scarcely 

 succeeds in) giving an explanation of the additional terms in 

 Van der Waals' equation for a gas while he has not previously 

 explained the occurrence of the terms in the equation of a perfect 

 gas itself. 



I eaving such points of mere exposition, we turn to the discus- 

 sion of the problem (on p. OS) of the abnormal lowering of freezing- 

 point of strong solutions of calcium chloride and aluminium 

 chloride. The writer is correct, we think, in considering this to 

 be a consequence of hydration of the dissolved salt. But we do 

 not think the reasons for his decision to be very illuminative. 

 It is not so much a question of there being Jess free water owing 

 to the hydration ; for, since the total volume is not thereby much 

 changed, we would not expect as a consequence much influence 

 (on the gas-theory) upon the osmotic pressure. The important 

 fact to emphasize is that the size of the molecule is thereby 

 increased, and just as in the case of a gas a large value of b in the 

 gas equation means a large pressure (other things being equal), so 

 in this case an abnormally great osmotic pressure is indicated; 

 and this carries with it (owing to a property of all isotonic solu- 

 tions) an abnormal lowering of freezing-point. 



Some elementary calculus is employed in the section on chemical 

 dynamics. It is of a very simple kind and does nothing except 

 improve the exposition. The student is in consequence called 

 upon less to accept results on trust without the argument being 

 presented to him. 



-Besides all the phenomena which we would expect to be dealt 



