Notwes respecting New Books. 309 
Realizing, no doubt, the difficulties which are connected with 
the more general mode of treatment, Professor Planck has, in the 
treatise before us, adhered to the standard method, in which the 
perfect gas is used as a convenient mental peg on which to hang 
the wider generalizations of the science. But the perfect gas, 
having performed its function, is soon abandoned in favour of 
those more general principles which have revolutionized the study 
of chemical reactions, and a large portion of the book deals with 
the applications of thermodynamics to problems of chemical 
equilibrium. The general plan of the book may be here briefly 
outlined. Part I. deals with Fundamental Facts and Definitions ; 
Part IT. with the First, and Part III. with the Second, Law of 
Thermodynamics; while the concluding Part IV., which forms 
rather more than one-half of the book, contains applications to 
special states of equilibrium. 
A careful study of this work, and especially of Part ILI., which 
contains a most careful discussion of the validity of the Second 
Law, will well repay the trouble spent upon it. The translation 
is well done, and there appear to be very few slips or misprints. 
On p. 40, line 13 from the top, “definite” should be substituted 
for ‘*‘ different,” and there is a somewhat remarkable slip at the 
begining of § 86, p. 58, where we read the surprising statement 
that “ only the specific heat at constant pressure, Cos is capable of 
direct experimental determination, because a quantity of gas 
inclosed in a vessel of constant volume has far too small a heat 
capacity to produce sufficient thermal effects on the surrounding 
bodies.” This statement would seem to show that neither the 
author nor the translator is aware of Dr. Joly’s brilliant researches 
and his complete success in determining ¢, experimentally by means 
of his steam calorimeter. 
Die Schule der Chemie. Erste Einfiihrung im die Chemie fiir 
Jedermann. Von W. Ostwatn, O. Professor der Chemie an der 
Universitit Leipzig. Erster Teil. Allgemeines. Mit 46 in den 
Text eingedruckten Abbildungen. Braunschweig: F. Vieweg 
und Sokn. 1903. Pp. vii+186. 
Ir is not often that a great man of science condescends to write a 
very elementary text-book—one, that is to say, which will be 
intelligible to “the man in the street.” The temptation to assume 
for granted or self-evident many results which to the non-scientific 
mind present considerable difficulties is one not easy to resist. 
The book under review is a striking testimony to the remarkable edu- 
cational ability of its distinguished author, and after perusing it one 
cannot help wishing that all one’s teachers had possessed Professor 
Ostwald’s gift of adapting himself to the exact mental level of his 
pupil. The instruction is conveyed in the form of a dialogue 
between teacher and pupil, and the method followed will prove full 
of interest to elementary teachers. The book affords as delightful 
reading as Tyndall’s ‘Forms of Water,’ and the “teacher's ” 
statement that “‘ Chemie zu lernen ist ebenso lustig, wie im Walde 
zu spazieren” is fully justified. The present volume deals with 
