May 21, 1914! 
NATURE 
293 
or up-grade process of evolution from elements of 
low atomic weight to elements of higher atomic 
weight occurs anywhere in the cosmos. If evolu- 
tion is universally true in principle some process of 
this order must have occurred in the past and may 
be occurring now. Laboratory results which are 
indicative of “transmutation” in the sense of 
degradation are becoming more and more incor- 
porated with modern chemical doctrine, but ex- 
perimental evidence of the opposite process can 
scarcely be considered at present conclusive. The 
notion of utilising the energy of degradation of 
radium emanation for transmutational purposes 
was presumably based on the expectation of de- 
gradation rather than of aggregation. 
The question of the evolution of the chemical 
elements is an old one, and the suggestion of 
evolution offered by the periodic law has been 
taken up by many writers whose speculations are 
no doubt familiar to chemists. The author of the 
present work does not discuss any of these specu- 
lative attempts to trace the lines of descent, 
although he gives some very useful tables sum- 
marising existing knowledge with respect to the 
disintegration products of the radio-active ele- 
ments. But in directing attention once again to 
the evidence of evolution furnished by the study 
of stellar spectra by that comparative method 
which will always be recognised as the work of 
Lockyer and his school, Prof. Letts does good 
service by reminding chemists that the newer 
developments of their science have enhanced the 
importance of astrophysical (why not astrochem- 
ical?) work to an extent quite undreamt of at the 
time when the spectroscope was first brought to 
bear upon these problems. 
If any justification for undertaking the part of 
a critic is required on the present occasion it 
may be permissible to express regret that the 
author should have devoted so much space to re- 
printing long extracts from the original writings 
of the authorities quoted. All the books and 
papers referred to are easily accessible, and Dr. 
Letts gives evidence of being such a very clear 
thinker when he deals with his subject in his own 
way that we should much have preferred to read 
his own version and criticisms. This particularly 
applies to the last chapter, which is devoted to an 
account of the views of Arrhenius in his now well- 
‘known book on ‘Worlds in the Making” pub- 
lished-in 1908. The direct bearing of the views 
set forth in that work on the fundamental prob- 
lems of modern chemistry are not very obvious, 
and we should have been glad if Dr. Letts could 
have given less space to the extracts from the 
said book and more space to the discussion of the 
special reasons for including the subject in his 
NOw325, VOL: 93! 
| own volume. 
The main contribution to purely 
“astrochemical”’ thought which must be credited 
to Arrhenius would appear to be the recognition 
of heat as an associative as well as a dissociative 
agency. In theories of cosmical evolution, this 
point may have been insufficiently realised, al- 
though the possibility of endothermic combination 
between certain elements under high pressure in 
the sun and stars cannot be generalised into a 
universal process for all kinds of matter without 
further evidence. 
Enough has been said, however, to warrant the 
statement that the author has produced a most 
useful and suggestive little volume which may be 
profitably read by chemists of both the older and 
younger generations. R. MELpbota. 
GEOLOGY AND GEOGRAPHY. 
(1) La Face de la Terre. (Das Antlitz der Erde.) 
By Prof. Ed. Suess. Traduit de: 1l’Allemand 
avec 1’Autorisation de l’Auteur et Annoté sous 
la Direction de Emm. de Margerie. Tome 3. 
(3 Partie.) Pp. xit+957—1360. (Paris : Armand 
Colin, ‘congs) Price 12’ frances. 
(2) Traité de Géographie Physique. Clmat— 
Hydrographie—Relief du Sol-—Biogéographie. 
By Prof. Emm. de Martonne. Deuxieéme 
Edition. Pp. xii+922. (Paris: Armand Colin, 
roLg.)\) Hace: 22. francs: 
HE two volumes before us strikingly illus- 
trate the principle that scientific geography 
as distinct from mere geographical description 
—must be based on the deductions of geology and 
the physical sciences; and no less do they indicate 
how much geology looks to gain from the study 
of the present features of the earth’s surface, and 
of terrestrial processes now going on upon it. 
(1) That M. Margerie’s French edition of the 
great work of the distinguished Austrian geologist 
is not a mere translation has been already pointed 
out in the pages of Nature. The judicious notes, 
bringing the text up-to-date, with the exhaustive 
references to recent literature and the numerous 
additional illustrations, make the book an absolute 
necessity in every scientific library. In this third 
part of vol. iii, M. Margerie has reached the 
penultimate section of his great task, and an 
additional coloured plate, with eighty new illus- 
trations in the text, give a measure of the import- 
ant additions which have been made to the original 
work. 
(2) Nor are the additions which have become 
necessary to the comprehensive volume of Prof. 
de Martonne less abundant and important. Since 
the first edition appeared four years ago, the author 
reminds us that geographical research has added 
largely to our knowledge—not the least striking 
