660 
tion with the use of neutral copper sulphate is 
recommended instead of the acid solution of 
the double chloride of potassium and copper, 
which has been shown to be more exact by the 
American Committee on Standard Methods. 
With revised tables of atomic weights, pub- 
lished annually by both the American and 
German Chemical Societies, it seems hard to 
find an excuse for a list which includes such 
values as Al, 27.5; Mg, 24.0; Si, 28.0; Cr, 
52.5; Zn, 65.0. Antiquated values are also 
given for the specific gravity and weight of one 
liter of hydrogen. 
While defects in the book have been pointed 
out at some length, it would be unfair not to re- 
fer to the large amount of valuable material to 
be found in its pages. 
The frequent tables of analysis for commer- 
cial products give, in concise form, directions 
which will be very useful to the working 
chemist. The specifications for many substances 
used by railroad companies form a unique and 
excellent feature. And, while pyrometry, 
electrical units and energy equivalents do not 
properly belong in the domain of chemistry, 
many chemists will find them useful. 
W. A. Noyes. 
Ausgewdhlte Methoden der analytischen Chemie. 
Von ProFEssOoR Dr. A. CLASSEN. Erster 
Band unter Mitwirkung von H. Cloeren. 
Braunschweig, Friedrich Vieweg und Sohn. 
1900. 18mo. Pp. xx+ 940. Figs. 78. 
Price, M. 20. 
Notwithstanding the astonishing number of 
books bearing upon analytical chemistry which 
appear yearly, it is probably within bounds to 
say that, until recently, only those of Fresenius, 
Bockmann, Bolley, Post, and possibly that of 
Crookes, have generally been regarded as ful- 
filling the requirements as to scope and relia- 
bility of a satisfactory book of general reference. 
In the last few months, however, three works 
of wide range and excellent promise have ap- 
peared—namely, those of Carnot (‘Traité d’an- 
alyse des substances minerales’), Lunge (‘Che- 
misch-technische Untersuchungs-methode’) and 
this work of Classen. Classen’s work differs, 
however, from those of Lunge (a continua- 
tion of that of Bockmann), Bolley, and Post, 
SCIENCE. 
[N. S. Vou. XIII. No. 330. 
in that he presents his subject matter in such a 
way as to emphasize rather the general useful- 
ness of the methods described than to present 
schemes for the analysis of particular bodies, 
although the application of the methods to 
special cases is adequately treated. On the 
other hand, Classen’s work differs from those 
of Fresenius and Carnot, in that he has pre- 
pared the book for the use of technical chemists 
and advanced students to whom the general 
operations of analytical chemistry, such as 
weighing, filtering, and the like, are known. 
These are, therefore, omitted, and he proceeds 
at once to the description of particular methods. 
The present volume includes only the metals 
and metalloids. Methods suitable for the quali- 
tative detection of each are described, followed 
by procedures for their quantitative determina- 
tion by volumetric, gravimetric, colorimetric or 
electrolytic methods, the selection having been 
determined upon, he states, only after tests 
made by him, his assistants or pupils, or, in 
some instances, after he had become convinced ° 
of the accuracy of the processes through pub- 
lished criticism. The descriptions of the pro- 
cedures for the determination of the metals 
are, in turn, followed by those of methods for 
such separations from other elements as occur 
in ordinary analytical practice, and, in addition 
to the foregoing, special schemes are given for 
the analysis of bodies of technical importance, 
such as irons and steels, aluminum and its 
alloys, cements, clays, glasses, zinc ores and zine 
dust, chrome iron ore and chrome steel, uranium 
ores, platinum ores and residues, ‘ osmiridium,’ 
‘platiniridium,’ fertilizers, liquid ammonia, 
ammoniacal liquors, and a scheme for rock 
analysis. ° 
The value of this book as a work of reference 
is also much enhanced by the introduction of 
matter relating to the rarer elements. The 
methods described for the separation of the rare 
earths by fractional precipitation and the an- 
alysis of monazite sand, as well as of the ma- 
terials employed in the manufacture of mantles 
for incandescent lamps, appear to be specially 
complete. 
The author deplores the general absence in 
text-books and journals of statements indicat- 
ing the basis of the stoichiometrical calcula- 
