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THURSDAY 51 
A SYSTEM OF 
A System of Physical Chemi 
McC. Lewis. Two. -vols. 
*523. Vol. ii.,. pp. vii+552. (London: 
mans, Green and Co., 1916.) gs. net each vol. 
HYSICAL chemistry in the present-day sense 
of the term may be said to date from 1887, 
the year in which Ramsay came to London, 
Ostwald was appointed to the chair in Leipzig, 
and the Zeitschrift fiir phystkalische Chemie was 
_ founded by Ostwald and van’t Hoff. Although 
‘many pioneers, amongst whom may be mentioned 
Deville, Debray, Guldberg and Waage, Gibbs, 
Horstmann, Berthelot, Thomson, Harcourt and 
Esson, Gladstone, Le Chatelier, and Lemoine had 
prepared the way for the new development in 
chemical science, it was the combined influence of 
van’t Hoff, Arrhenius, Ostwald, and Ramsay that 
gave direction and strength to the new current of 
thought and research. 
It is a remarkable fact that during this period 
of nearly thirty years the English-speaking 
peoples of the world have had to depend chiefly on 
works written in German, or their translations into 
English, for the accepted standard treatises on 
the subject. The ‘“ Lehrbuch” of Ostwald, the 
“Theoretische Chemie ”’ of Nernst, and the “ Vorle- 
sungen ” of yan’t Hoff were for many years with- 
out a serious competitor. A change in this state 
of affairs was brought about by the appearance of 
the excellent series of ‘‘Text-books of Physical 
Chemistry ” edited by Sir William Ramsay. But 
as these were mostly in the nature of special 
treatises on different branches of the subject, the 
student desirous of obtaining a compact and 
rounded, and at the same time fairly comprehen- 
sive, View of physical chemistry as a whole had 
still to have recourse to the works previously men- 
tioned. Yet none of these was entirely satisfac- 
tory. Ostwald’s ‘‘ Lehrbuch,” though unexcelled 
in its historical treatment of the subject, was too 
-cumbrous, was marred by its author’s unfortunate 
attempt to “energeticise”’ thermodynamics, and 
has not been kept up to date. Nernst’s otherwise 
excellent treatise repelled the student by its open- 
ing chapters, which presented the subject of 
thermodynamics in a NHelmholtzian form un- 
familiar to English students, but so generalised, 
so condensed, and so careless in reasoning that 
few students could separate the gold from the 
dross. Finally, the lectures of van’t Hoff, though 
the work of a master-hand, scarcely covered the 
required field of study in a sufficiently comprehen- 
sive manner. 
_ The present work, which appears as the latest 
volume of Sir William Ramsay’s series of text- 
books, differs radically from its predecessors 
inasmuch as it essays to present the reader with a 
fairly comprehensive ‘‘ System of Physical Chemis- 
try.” In this respect it is worthy of especial con- 
sideration and attention. It may be said at once 
NO. 2446, VOL. 98] 
iy Prof. W. C. 
Vol.i.; pp. xiv+ 
Long- | 
that in its arrangement of matter, lucidity of style, 
and comprehensive unity of design it is' destined” 
to become the standard general treatise on the: 
subject of physical chemistry for English-speaking 
students. 
The frontispiece consists of a table indicating a 
“philosophical” classification of the subject. 
This is very interesting, and will be of great’ 
service in giving the student a reasoned survey of 
the field to be traversed. The main division is 
into systems in equilibrium and systems not in’ 
equilibrium. The subdivision of these. is. based 
partly on the nature of the subject-matter and 
partly on the method of treating it. This want of 
uniformity in the system of classification is, how- 
ever, no defect, as it corresponds to the natural 
development of science. The author is to be con- 
gratulated on this emphasising of the philosophi- 
cal aspect of his subject, an aspect which is all too 
frequently ignored by the authors of scientific 
treatises. For practical purposes the work is 
divided into two volumes. Vol. i. deals with the 
subject from the classical kinetic-molecular point 
of view. Vol. ii. is divided into two parts, part i. 
being entitled ‘‘Considerations based upon 
Thermodynamics,” and part ii. “ Considerations 
based upon Thermodynamics and __ Statistical 
Mechanics.” 
This method of division has a philosophical and 
historical as well as a practical didactic basis. As 
Perrin has pointed out in the beautiful preface to 
“Les Atomes,” there are two methods by means 
of which the human mind advances in its under- 
standing of the external world. In one case ‘“‘on 
généralise des résultats d’expérience, mais les 
raisonnements ou les énoncés ne font intervenir 
que des objets qui peuvent étre observés ou des 
expériences qui peuvent étre faites.” This is 
essentially the method of the “classical” thermo- 
dynamics, on which so much of the science of 
physical chemistry is based. But there is also 
another method—“deviner l’existence ou les 
proprictés d’objets qui sont encore au dela 
de notre connaissance, expliquer du visible com- 
pliqué par de Vinvisible simple, voila la forme 
d’intelligence intuitive A laquelle, grace 4 des 
hommes tels que Dalton’ ou Boltzmann, nous 
devons 1|’Atomistique.”’ It is to this that we owe 
not only the beginnings of chemical science, but 
also the latest advances. The trend of modern 
physical chemistry is largely in the direction of 
“ Atomistique.” 
The author’s presentation of the subject has also 
an important didactic advantage. ® Students in- 
variably find chemical thermodynamics difficult, 
but read with comparative ease an exposition 
based on a simple kinetic-molecular method of 
treatment. In vol. i. they will find the latter, 
enlivened and brought up to date by an account 
_ of the work of Einstein, Perrin, and Svedberg on 
“molecular reality,” and a discussion of the elec- 
tron theory of matter, the structure of the atom, 
and the transmutation of the elements. Part i. 
of vol. ii. contains a good account of the thermo- 
dynamical treatment of chemical problems, includ- 
Cc 
