504 
NATURE 
[Juty 8, 1915 

and there are plenty of thumb-nail sketches of 
them. It is interesting to know that Robert 
Brown, whom Humboldt calls “the glory of 
Great Britain,’ was shy and a dead weight at a 
dinner party, as it explains why he was thought 
morose. This was not Humboldt’s fault, as at a 
breakfast at Murchison’s he “talked without any 
sort of stop for three hours.” Carlyle “is very 
pleasant to talk to, he is so very natural”; he 
said Cardinal Newman “has no occiput,” and 
Woolner seems to have found it was more than a 
metaphor. It is difficult to resist quotation. But 
the opinion of Sir Francis Galton cannot be 
omitted, “that truth or falsehood in a nation is 
merely a question of geography, and that the 
nations who have not got the article do pretty 
well without it.” 
COLLOID CHEMISTRY. 
The Chemistry of Colloids and some Technical 
Applications. By Dr. W. W. Taylor. Pp. 
vili+328. (London: Edward Arnold, 1915.) 
Price 7s. 6d. net. 
HIS work can claim to meet a_ long-felt 
want with more justice than the majority 
of publications heralded by that familiar phrase. 
Until its appearance it has been necessary to 
refer students to German text-books, many of | 
which are extremely difficult reading for even fair 
scholars of that language, while most of them 
devote considerable space to the discussion of 
theories of the soundness of which the beginner 
cannot be, and should not be tempted to imagine 
himself, a judge. 
It'is one of the merits of the present text-book 
that by far its larger portion consists of a lucid 
and concise account of observed facts, the descrip- 
tion of which precedes the discussion of theories 
advanced to explain them everywhere but in the 
section dealing with adsorption, where the re- 
versal of this order is undoubtedly the only peda- 
gogically sound procedure. The text is divided 
into four parts: general properties of colloids; 
methods of preparation; adsorption and applica- 
tions of colloid chemistry. The subjects indicated 
by these headings are treated clearly and ade- 
quately, the instructions for experimental work 
being particularly satisfactory—with the excep- 
tion, perhaps, of ultra-microscopy. This is a point 
which always presents difficulty, as a knowledge 
of the principles of high-power microscopy must 
be presumed which is by no means general. As 
regards theory, the reviewer has been particularly 
struck with the very lucid summary of von 
Weimarn’s theory of dispersoid formation, which 
gives the student all that is essential, while saving 
NO. 2384, VOL. 95] 

him the labour of wrestling with the extraordin- 
arily difficult style of the original. 
The chapters on adsorption generally follow 
Freundlich, but include some recent and impor- 
tant work on the behaviour of sols in contact with 
other liquid phases. A very. necessary warning 
against identifying phenomena only superficially 
similar with adsorption, and against using the 
latter as a facile explanation of obscure pro- 
cesses, is sounded repeatedly. In the concluding 
section the application of colloidal chemistry to 
the explanation of various phenomena is illus- 
trated by a number of examples selected at random 
and including the unavoidable dyeing and tan- 
ning. Here, also, the author is careful not to 
countenance any extravagant claims on behalf of 
the science, and the student will be left under the 
correct and stimulating impression that colloidal 
chemistry can show—in the words of the famous 
epitaph—“ great achievement but still greater 
promise.” 
The book is well printed and adequately illus- 
trated, and may be unreservedly recommended to 
all students desirous of a sound knowledge of 
what is probably the most widely important, and 
certainly the most fascinating, branch of physical 
chemistry. 

GEOGRAPHY AS A SCIENCE. 
The Teaching of Geography. By B. C. Wallis. 
Pp. vili+221. (Cambridge: At the University 
Press, 1915.) Priceyasssodammnet. 
ERHAPS no school subject, in recent years, 
has been so much discussed as that of 
geography. The old meaningless lists of names 
of places, “famous for” all kinds of curious, as 
well as important things, has been ruthlessly 
consigned to the scrap heap. Exactly what is to 
take its place no one has yet determined, and each 
expert goes his own way and proclaims his 
own gospel. Geography—economical, physical, 
regional, historical, practical—has annexed so 
many other domains of learning, that the special- 
ists differ within very wide limits, and the non- 
specialist teachers are overwhelmed by conflicting 
claims, arguments, and interests. 
This book, by Mr. B. C. Wallis, covers most 
of the questions that interest the practical teacher, 
and on each and all of them he has much to say 
that is valuable. He is a teacher himself, that 
is, a teacher of children; some of the people who 
theorise upon the subject are only teachers of 
adults. 
Mr. Wallis would have us divide our school 
schemes of work into three sections—descriptive 
in the early stages; transitional for the inter- 


