REVIEWS 517 



After almost avoiding the old story in explanation of the colour changes of indi- 

 cators—charging the ions with it — we find on p. 20 the student is advised to consult 

 headquarters for further information. Surely the work of the past ten years is also 

 worthy of the student's attention. 



On this page is also to be found the following delightful explanatory 

 statement : " Many colour changes are due to the conversion of one ion into 

 another. Thus the monovalent permanganate anion is a deep purple, while that 

 of the divalent Mn" cation is very light pink. Hence, when the permanganate 

 MnO', is reduced to the divalent Mn" cation by the action of reducing agents, a 

 striking loss of colour follows." 



From the student's point of view great exception must always be taken to such 

 dogmatic statements as this. Apart from its being illogical to make use of circum- 

 gyratory argument, to fling such paragraphs at any student can only lead to disas- 

 trous results. No matter what the subject dealt with may be, the educational value 

 of this kind of teaching is nil. 



Apart from these aspects, bearing in mind the modest size of the volume, a 

 surprising store of very useful information is to be found amongst its pages ; both 

 as regards the behaviour of simple substances and of mixtures lowards chemical 

 agents. 



It would be unusual, but nevertheless refreshing, to find in books of this 

 description some statement to the effect that although the tables of separation 

 they contain are those generally employed, other schemes of separation are not 

 only possible but are sometimes used. There seems to be a growing idea that 

 tables of separation are akin to the laws of the Medes and Persians : that there 

 is no alternative scheme of procedure : that magnesium, for example, is never 

 precipitated in the wrong group, and so forth. The time devoted to this branch of 

 chemical training is generally so short that a scheme of separation cannot be 

 worked out individually, but a short clear statement of the facts of the case would 

 serve a very useful purpose. 



The chapter describing the properties of some of the rarer elements forms 

 quite a good addition to the book. 



As a bench companion, Dr. Perkins' book cannot fail to be of great assistance 

 to those who engage in qualitative analysis. J. V, Eyre. 



Physical Chemistry, its bearing on Biology and Medicine. By J. C. Philip, 

 M.A., Ph.D., D.Sc. [Pp. ii + 312.] (London: Edward Arnold, 1910. 

 Price "js. 6d. net.) 

 This work, as its name implies, is intended more particularly as an introduction 

 to Physical Chemistry in its appHcation to the chemistry of vital processes. 

 Whilst a great part of the book, of necessity, is pure physical chemistry, those 

 ^arts which deal with the biochemical aspect of the subject are by no means 

 valueless to the student of general chemistry : in fact, they might be read with 

 advantage as an introduction to a broader view of the subject that would temper 

 the purely physical attitude so commonly adopted, which does not appeal to the 

 average student of chemistry. It is questionable whether the ordinary medical 

 student would derive much benefit from such a book or is intended to ; but it should 

 be useful to those who wish to attain to more than the smattering of biochemistry 

 required for examination purposes, to whom a knowledge of the main principles 

 of physical chemistry is invaluable if not essential. The elements of the subject 

 are treated of at some length and most of the phenomena are gone into sufficiently 

 to enable the student to become further acquainted with them comparatively 



