540 



SCIENCE 



[Vol. LVI, No. 1454 



tlie minute attention devoted to absorption it is 

 a disappointment that sueh a meagre treatment 

 is given of the general relations involved under 

 the head of surface tension. This treatment is 

 confined practically to dealing with the appli- 

 cation of the Willard Gibbs surface concentra- 

 tion law to colloidal particles. One wonders 

 why the Brownian movement phenomenon is 

 attached to this chapter as there is given merely 

 a sketchy account which would fit in better 

 under the chapter dealing with "properties of 

 colloidal solutions." 



The remaining chapter (V) of the general 

 theory is on "coalescence." This chapter ap- 

 peals to one as ideal in its scope in that it 

 fulfils the aim laid down by the author in his 

 preface. General phenomena are adequately 

 treated and the application to colloidal work is 

 admirably clinched at its close. 



Thus slightly more than one half of the book 

 is devoted to a more or less general treatment 

 of absorption, surface tension, Brownian move- 

 ment and coalescence. The remainder deals 

 with the preparation and peculiar properties 

 of the following classes of colloidal solutions: 

 (1) suspensoids (Ch. VI and VII); (2) emul- 

 soids (Oh. VIII and IX); (3) non-aqueous 

 colloidal solutions (Ch. X) ; (4) fog and smoke 

 (Ch. XI); and (5) solid colloidal solutions 

 (Ch. XII). The last chapter (XIII) contains 

 a card catalog account of the thickness of films. 

 The chapter on the properties of colloidal 

 solutions seems to be quite inadequate for a 

 volume which professes to be a complete treat- 

 ment of the general theory. While many inter- 

 esting facts regarding these solutions are given, 

 there is a lack of logical method and per- 

 spective in their arrangement. For example, 

 a rather long and intrinsically interes,ting sec- 

 tion is devoted to color phenomena; but the 

 colloidal chemist will hardly admit that this 

 particular property is as important as the elec- 

 ti'ical properties of these solutions or as the 

 phenomenon of coagulation by electrolytes, 

 each of which is given rather less space. 



Perusal of the chapter on gelatinous pre- 

 cipitates and jellies justifies the author's state- 

 ment in the preface that there is not much 

 known about these materials. What is known 

 is given in a very readable shape. More might 



have been given regarding the evidences of the 

 existence of a structure in protein solutions as 

 outlined by Professor Brailsford Robertson. 

 It is interesting to have the criticism of a 

 physical chemist on the recent work of Loeb, 

 as given in this chapter. 



The remainder of the book consists in gen- 

 eral of an encyclopedic account of experi- 

 mental facts regarding emulsions, foams, fog 

 and smoke : regarding this phase of colloidal 

 work there is known very little more than a 

 series of interesting, but more or less detached, 

 experiments, coupled with some very important 

 commercial applications such as ore fiotation 

 and the Cottrell process. It is sometimes an- 

 noying to find the practical application of ex- 

 perimental facts so far in advance of our the- 

 oretical knowledge of their causes. 



The book can be recommended as a mine of 

 information on most of the subjects dealt with. 

 However, from the point of view of an attempt 

 to give a final treatment of the general theory 

 of coUoidal solutions it is rather disappointing. 

 Such a general treatise demands not only the 

 eseeUent treatment here given of absorption 

 jDhenomena but just as ample treatment of such 

 questions as (1) the relation of surface tension 

 phenomena to small divisions of matter, (2) 

 the Brownian movement of small particles, (3) 

 the electrical charges of small suspended parti- 

 cles, electro-endosmose phenomena, and coagu- 

 lation of electrolytes, and, say, (4) the physical 

 properties of jellies. One would be justified 

 in expecting in addition an attempt to account 

 for the limiting size attained by these particles 

 in suspension in any given case. In fact one 

 can hardly say "the general theory of the sub- 

 ject once cleared up" with the conviction that 

 such a desirable state of affairs is yet accom- 

 plished. 



As is true with all the volumes of this series 

 (International Chemical Series), the workman- 

 ship is excellent, the references very ample, 

 and the appearance of the whole very attractive 

 indeed. This particular volume will be read 

 with interest and pleasure. 



E. r. BUETON 



Untversitt op Toronto, 

 Canada, 

 October 14, 1922 



