JANUARY 31, 1907 | 
NATURE 317 
of the subject it would have been better to omit these 
and to have utilised the space so saved in filling up 
some of the gaps left in the theoretical treatment, and 
to which we refer later. The same remarks apply to 
some extent to the sections on the separation of 
organic compounds, which are valuable in so far as 
they treat of the law of partition and the distillation 
of mixtures of miscible and of non-miscible liquids, 
but much space is taken up by descriptions of work- 
ing methods unnecessary to the student who has 
attended an experimental course in the subject, and 
insufficient for the instruction of the inexperienced. 
Again, in a book of limited space, why lavish two 
whole pages on illustrations of a large table carry- 
ing a small combustion furnace, with tube and 
fittings, and of an ordinary type of reflux apparatus! 
The book could hardly have suffered from the 
omission of these, together with most of the remain- 
ing illustrations, the instructional value of which, for 
example, of the sketch of the superseded distilling 
tube. of Le Bel and Henninger, or of the large 
acetylene burner on p. 95, is not always apparent. 
Having found fault so far with the introduction, 
and that chiefly because of its failure to reach the 
standard of excellence set up by the preface, we must 
state that the theoretical discussions throughout the 
remainder of the book are clear and satisfactory, as 
are also the later portions of the introduction dealing 
with the calculation of formulae and molecular 
weights, the thermochemistry of carbon, and the 
general properties and classification of the compounds 
of carbon according to their structure. 
Of the 585 pages remaining after the introduction, 
317 are devoted to the consideration of the alicyclic 
compounds and thirty-nine to the cyclic groups inter- 
mediate between these and benzene. This, with its 
derivatives, is described in 175 pages, leaving only 
fifty-four for the discussion of the heterocyclic com- 
pounds, the glucosides, the albuminous substances, 
and the soluble ferments. As the book contains com- 
paratively little small print and the margins are 
ample, it follows that some of the groups must be 
treated in but a scanty manner, if at all, those in- 
cluded under the three last headings being the chief 
sufferers from this cause. Certainly in the space at 
his disposal the author gives a surprisingly compre- 
hensive review of the more important of the hetero- 
_ cyclic compounds. 
The arrangement of the alicyclic compounds differs 
in several respects from that to which we are accus- 
tomed. The esters appear under the old name of 
‘“compound ethers’? amongst the ethereal derivatives 
of the alcohols, whilst we do not make acquaintance 
with the ketones or the aldehydes until after the de- 
scription of the monocarboxylic acids and the sub- 
stances derived from these. A few helpful tables are 
given showing the principal mono- and di-basic acids 
with their main physical properties, and of the 
aldoses with the corresponding penta-hydroxy-acids. 
The carbohydrates are followed by a succinct account 
of the derivatives of carbonic acid. 
‘In the course of the chapters on the alicyclic com- 
NO. 1944, VOL. 75] 
pounds, optical activity and the hypothesis of the 
asymmetric carbon atom, the dynamics of esterifi- 
cation, the nature and properties of the pseudo-acids, 
the constitution of the complicated derivatives of 
cyanogen, and the employment of the inversion of 
cane sugar in the measurement of the strength of 
acids, are clearly if briefly explained. Similar concise 
discussions of the question of the structure of the 
benzene nucleus—including the arguments in favour 
of the centric formula, the application of Thiele’s 
hypothesis of partial valencies, and the bearing of 
the optical properties—and of the constitution of the 
diazonium salts and the diazotates and their relation 
to the nitrosamines are to be found in the chapters 
on the aromatic compounds. We must remark at 
the same time that there is no mention of several 
important matters, such as the difficulty of esterifying 
certain carboxylic acids by boiling with alcohol and 
an acid, and Victor Meyer’s explanation of this on 
the assumption of the so-called “‘ space interference,” 
nor can we find any account of Gustav Komppa’s 
synthesis of y-camphoric acid. 
References to the original literature are of great 
value in all beyond the most elementary text-books, 
and would have been specially so in a work intended 
for the use of students otherwise unguided; here such 
references are entirely wanting. Only occasionally 
even does the description of a reaction, a synthesis, 
or a theory suggest its author’s name. 
The book is provided with a subject index, but not 
with a table of contents; fortunately, the page-head- 
ings are well arranged. Although some portions of 
the book are decidedly disappointing, on the whole 
it can hardly fail, if conscientiously read, to broaden 
the views even of students considerably beyond an 
elementary stage of knowledge in organic chemistry. 
Gaye 
SOME OPINIONS ON TEACHING 
MECHANICS. 
The Teaching of Elementary Mechanics. Discussion 
which took place at Johannesburg at the British 
Association Meeting in South Africa on August 29, 
1905, in Section A, Prof. Forsyth, President of the 
Section, in the Chair, together with written 
criticisms and a paper by C. E. Ashford, M.A. 
Edited by John Perry. Pp. 74. (London: Mac- 
millan and Co., Ltd., 1906.) Price 2s. net. 
HIS little book is another addition to many out- 
comes of Prof. Perry’s never-failing activity 
and energy in trying to improve the teaching of our 
schools in matters connected with elementary science. 
At the British Association in Johannesburg last year, 
Prof. Perry, in the midst of his arduous duties as 
general treasurer of the association, found time to 
open a discussion on the teaching of elementary 
mechanics, and, not content with this, he collected 
the remarks of all the speakers at the meeting, and 
specially engaged a ‘‘chiel takin’ notes’’ to keep 
a record of their speeches. He next wrote round to 
a large number of teachers and others in England, 
