APRIL I, 1915] 
NATURE 
117 

knowledge of these elusive elements, some forty 
of which are crowded into ten places of the con- 
ventional periodic classification. 
(4) The French book on analysis and synthesis 
is the fifth volume of an Encyclopedia of Applied 
Chemistry. It includes five sections on “ Organic 
Analysis,” by M. Hanriot; “ Pharmaceutical Pro- 
ducts,” by P. Carré; “Synthesis of Colouring 
Matters,” by A. Sergewetz; “Production of Per- 
fumes,” by E. Charabot; “Saponification,” by A. 
Hébert. It is therefore in feality a series of five 
monographs, bound together in one volume and 
grouped under a convenient general title. It 
forms a companion to a similar volume on the 
theory and practice of mineral analysis, but might 
with advantage have been issued in separate parts, 
as it is unlikely that many workers would attempt 
to cover the wide field included in this volume. 
(5) Prof. Ostwald’s “Principles,” of which a 
fourth edition is now published, is an inorganic 
chemistry written from the point of view of the 
physical chemist. The ionic hypothesis occupies a 
place of honour throughout the volume. In the 
new edition a final chapter on the radio-active 
elements contains a somewhat full account of the 
three chief disintegration-series of radio-elements. 
(6) Mr. Williams’ book on the cyanogen com- 
pounds contains a detailed description of this im- 
portant series of compounds, arranged somewhat 
in the manner of a dictionary. Thus under the 
heading of ‘‘Thiocyanates,” details are given as 
to the composition and properties of thirty-two 
simple salts and a far larger number of double 
salts. The author has made a number of experi- 
‘ments himself, the results of which are now 
described for the first time, the “petty restric- 
tions” and “stereotyped methods” of the scien- 
lific societies having prevented him from publish- 
ing them through the usual channels. Fortun- 
ately, he has been able to avail himself freely of 
the work of others who have faced these obstacles. 
The book is therefore generously supplied with 
references to original literature, which render it a 
valuable guide to the subject with which it deals. 
(7) Mr. Oscroft’s book suffers from an unfor- 
tunate title. Intended primarily for senior classes 
of boys, it is described in the title as an “ad- 
vanced inorganic chemistry,” and in the text as 
a “Chemistry for advanced students.’”’ Such a 
description is misleading in the case of a book 
which devotes only one page to the Periodic Law, 
four pages to radio-activity, and five pages to 
spectrum analysis. Apart from this obvious error 
the book is a good example of the class of school 
text-books to which it really belongs. The author 
is in touch with the historical treatment, which is 
now becoming so important in the teaching of 
NO. 2370, VOL. 95 | 
5) 
elementary chemistry, and promises also to 
effect, on the theoretical side, an improvement 
comparable with that which has resulted from the 
introduction in the laboratory of experiments 
based largely on the classical work of Scheele, 
Cavendish, and Priestley. The illustrations are 
scarcely equal to the standard of the text, and are 
not improved by labelling the gases as H, N, O, 
ete., in direct defiance of their recognised mole- 
cular formule. The formule given on p. 223 for 
persulphuric acid should be H,SO; (monobasic) 
and H,S,O, (dibasic), and the preparation on 
p- 242, described and indexed under persulphuric 
acid, refers obviously to pyrosulphuric acid. 
(8) The instructions used in the chemical labora- 
tories at Leeds in the teaching of elementary 
students have been expanded by Mr. Lowson into 
a small volume intended primarily for local use, 
but likely to prove acceptable in other laboratories 
where similar work has to be carried out. The 
book consists mainly of simple preparations, which 
are described in detail in order to economise the 
time of the teacher and to enable him to accommo- 
date the course to the varying abilities of different 
' students. Theoretical questions suggested by the 
experiments are, however, referred to from time 
to time, and a large number of additional exercises 
are provided in connection with the different pre- 
parations. 
(9) Luff and Candy’s “Chemistry for Students 
of Medicine” shows a marked improvement in 
each successive edition. The condensation of the 
whole of the chemical theory, including the 
periodic classification of the elements, into one 
preliminary section does not provide a practicable 
basis for actual class-teaching; but it may well 
prove convenient to a student who wishes to revise 
what he has learnt in a course of lectures arranged 
on a gentler gradient. Historical references are 
more frequent than in the earlier editions, as the 
author has found that these interest the student, 
and also enable him to trace the evolution of the | 
fundamental principles of chemistry, and thus 
appreciate their full significance. TMEV: 
OUR BOOKSHELF. 
The Germ-cell Cycle in Animals. By Prof. R. W. 
Hegner. Pp. x+346. (New York: The Mac- 
millan Co.; London: Macmillan and Co., Ltd., 
1914.) Price 7s. 6d. net. 
In this interesting book Prof. Hegner gives a very 
complete and clear account of the origin, structure, 
and continuity from generation to generation of 
the reproductive cells of the Metazoa. Owen 
appears to have been the first clearly to point out 
that the fertilised ovum gives rise to two kinds 
of cells: the first destined to form the differ- 
| entiated tissues of the new individual, the second 

