526 
NATURE 
[JuLy 25, 1912 
of tube-length, that “greater extension of the tube 
will give higher magnifications, but not better 
definition.”’ It cannot be too strongly insisted on, 
particularly to a novice, that microscope objectives 
are designed to work at a particular tube-length, 
and that the possibility of obtaining greater or less 
magnification by alteration of this is not to be 
contemplated. Again, the quality of penetration 
in an objective is referred to as if it were a point 
to be considered, whereas it might have been 
pointed out that penetration is dependent on 
numerical aperture and on focal length. One-half 
of the book is devoted to a description of common 
objects and methods of observing them. The 
descriptions given are clear and suitable for those 
to whom they are addressed. oles 1B 
OUTLINES AND PRINCIPLES OF 
CHEMISTRY. 
(1) Outlines of General Chemistry. By Prof. 
Wilhelm Ostwald. Translated with the author’s 
sanction by Dr. W. W. Taylor. Third edition. 
Pp. xvii+596. (London: Macmillan and Co., 
Ltd., 1912.) Price 17s. ‘net. 
(2) Grundlinien der anorganischen Chemie. By 
Wilhelm Ostwald. Dritte Auflage. Pp. xxii+ 
860. (Leipzig: Wilhelm Engelmann, 1912.) 
Price 18 marks. 
(1) HE new English edition (a translation 
of the fourth German edition) of 
Ostwald’s “Outlines,” the pioneer elementary 
text-book on general chemistry, is sure to receive 
a warm welcome on the part of English-reading 
students of chemistry. During the seventeen 
years which have elapsed since the preceding 
edition (in Prof. James Walker’s translation) was 
published, Ostwald’s “Outlines” had _ practically 
ceased to be known to the ordinary English 
student of chemistry; and the reason for this is, 
of course, to be found in the fact that during this 
interval other text-books, due in most cases to 
pupils of Prof. Ostwald himself, appeared both 
in this country and in America, which were written 
in a manner more suited, perhaps, to the mental 
aptitudes and to the manner of thought and train- 
ing of British and American students. ‘The treat- 
ment of the subject by Prof. Ostwald was, as it 
seems to the reviewer, somewhat too abstract and 
too philosophic for the average young student of 
chemistry in this country, who, partly through 
lack of taste for or training in philosophy, partly 
perhaps owing to our examination system, desires 
to have the facts and laws and theories of physical 
chemistry placed before him as _ clearly, as 
succinctly, and as concretely as possible. ‘This 
“defect” of the older editions the author has 
vecognised, and has to a great extent remedied; 
NO. 2230, VOL. 89] 
and even if it do not displace the indigenous text- 
books, the ‘Outlines ” will be valued, in any case 
by more advanced students and by teachers, on 
account of its breadth and originality of treat- 
| ment and the suggestiveness of its ideas. 
Net only have the earlier portions of the book 
been subjected to considerable rearrangement and 
the method of treatment been revised, but exten- 
sive alterations and additions have been made in 
harmony with the changes and progress which have 
taken place in this branch of science. Thus new 
chapters on gas ions and radio-activity and on 
micro-chemistry (colloid), chemistry) have been 
inserted; and the chapters on chemical kinetics 
and equilibrium and on electro-chemistry have 
been nearly quadrupled in extension. These addi- 
tions and extensions constitute probably the most 
interesting and readable portions of the book. 
To many chemists, perhaps, the most interest- 
ing and most welcome change which has occurred 
since the appearance of the previous edition is 
the change of mental attitude of Prof. Ostwald 
himself, to which he bears testimony in the fol- 
lowing words :— 
“T am now convinced that we have recently 
become possessed of experimental evidence of the 
discrete or grained nature of matter, which the 
atomic hypothesis sought in vain for hundreds 
and thousands of years. The isolaticn and 
counting of gas ions, on the one hand. . . and, 
on the other, the agreement of the Brownian 
movements with the requirements of the kinetic 
hypothesis . justify the most cautious 
scientist in now speaking of the experimental 
proof of the atomic nature of matter. The atomic 
hypothesis is thus raised to the position of a 
scientifically well-founded theory. ie 
The author, however, makes little use of the 
atomic theory in his treatment of the stoichio- 
metric relationships; and the discussion of the 
kinetic theory is now removed from its former 
position in the section dealing with the gas laws, 
and is relegated to a position near the end of the 
book, where it is treated in connection with the 
experimental evidence for it yielded by disperse 
systems. As the German edition on which the 
present English translation is based was published 
more than three years ago, it is conceivable that 
when another edition appears the author will take 
a step farther and will adopt the atomic and 
kinetic theories as the bases of treatment of the 
whole of stoichiometry. 
With regard to the section on the transformation 
products of the radio-active elements, it is to be 
regretted that in this English edition of 1912 
the author should have remained content with the 
summary given by Rutherford in 1905. Perhaps 
he finds his justification for this in the state- 
Ment. —— 
