MOAPRUL, #235. F144] 
NATURE 
185 
of the Society of Chemical Industry, should be 
balanced against those of Dr. Messel, his prede- 
cessor in this office. The workings of the latter’s 
mind in this. connection are adumbrated in the 
recent creation of two additional Chairs of “pure ”’ 
chemistry in the Imperial College of Science and 
Technology. However, if some degree of techni- 
cal proficiency is insisted on, the student cannot 
do better than to work through a selection of 
Mr. Arup’s thoroughly practical exercises in indus- 
trial analysis. 
(2) The authors have arranged this manual so 
that some knowledge of the principles of quanti- 
tative analysis may be acquired by a practical 
study of the three introductory sections, which 
include general principles, volumetric analysis, 
and gravimetric analysis, including electrolytic 
methods. Owing to its educative value, a thor- 
ough training in volumetric analysis is recom- 
mended when time permits of little or no gravi- 
metric work. The exercises included in the 
volumetric section form a very instructive and 
comprehensive series, involving the use of all the 
ordinary standard solutions. In view of the great 
importance attached by the authors to this side 
of analysis, it is perhaps allowable to suggest 
that a short description of the chemical nature 
of the organic indicators (methyl-orange, methyl- 
red, phenolphthalein) would have made the volu- 
metric section more self-contained. The prelimin- 
ary chapters are followed by sections devoted to 
colorimetric methods, systematic quantitative 
analysis, and the analysis of simple ores and 
alloys. _ Modern methods have been selected, 
among which may be indicated the estimation of 
potassium as perchlorate and the separation of 
iron from allied metals in acid solution by the 
use of “cupferron,’ the ammonium salt of 
nitrosophenylhydroxylamine. The appendix con- 
tains details of the preparation of this useful 
organic reagent. The section on gas analysis 
refers to the use of the simpler forms of appara- 
tus, such as the Lunge nitrometer and the appa- 
ratus devised by Hempel and by Orsat. Water 
analysis is included as an introduction to the esti- 
mation of substances present only in traces. The 
short section on ultimate organic analysis would 
have been rendered more complete by a_ brief 
reference to the Carius method for the halogens 
and sulphur. The determination of molecular 
weights includes details of the vapour density, 
cryoscopic and ebullioscopic methods. 
(3) This treatise is a very readable monograph 
on the sugars and their immediate derivatives, 
based on a course of lectures given at the Birk- 
beck College and in the University of Edinburgh. 
Rightly on account of their intrinsic importance 
NO, 23921, VOL: 93] 
three chapters each are devoted to cane sugar 
and glucose, these sections being a mine of in- 
formation in regard to these well-studied sugars. 
Among the many researches summarised may be 
_ mentioned ithose on the methyl glucoses, the 
| methyl glucosides, and their acetyl derivatives. 
One very interesting chapter is that relating to 
the configuration of the sugars, in which the 
' stereochemical relationships of these compounds 
are fully discussed. Succeeding chapters deal 
with dioses, trioses, tetroses, pentoses, together 
with the naturally occurring mannose, d-fructose 
(lavulose), and raffinose. The less important 
synthetic sugars are also reviewed. A synopsis 
is furnished of the glucosides found in plants, 
and the concluding sections deal with fermenta- 
tion and with the metabolic changes attending 
the use of sugars and allied carbohydrates as 
foodstuffs. References are given throughout to 
original sources of information, and the work is 
provided with complete author and subject 
indexes. 
(4) It is impossible within the space available 
to discuss in detail the hexite—pentite theory 
devised by the authors, in the first instance, to 
explain the constitution of the naturally occurring 
aluminosilicates, and subsequently employed to 
elucidate the chemical structure of clays, ultra- 
marines, glasses, glazes, porcelains, dental 
cements, hydraulic cements, and especially Port- 
land cements. It is assumed that five or six 
molecules of hydrated silica, Si(OH),, unite with 
partial elimination of water to form cyclic systems 
containing five or six silica residues, these com- 
plexes being termed respectively silicon pentite 
and hexite. Aluminium pentite and hexite arise 
in a similar way by the condensation of five and 
six molecules of hydrated alumina, Al(OH)s. 
The mineral aluminosilicates are regarded either 
as complex acids composed essentially of com- 
binations of these silicon and aluminium pentite 
and hexite rings, or as salts of these acids when 
the hydroxylic hydrogens are more or less re- 
placed by metallic elements. The felspars, micas, 
scapolites, etc., need no longer be regarded as 
molecular compounds belonging to different 
mineral groups; they can all be represented as 
unitary atomic compounds of the same class with 
definite structural formule. <A similar hexite— 
pentite hypothesis is employed to explain the 
constitution of vanadic, molybdic, and tungstic 
complexes. 
The translator, who has added several instruc- 
tive and critical notes, doubts whether the authors 
are justified in extending their views to explain 
the plasticity of clays. The authors’ theory has 
already been criticised by several writers, and 
