6/2 SCIENCE PROGRESS 



The Physical Properties of Colloidal Solutions. By E. F. Burton, B.A., 

 Ph.D. (Monographs on Physics edited by Sir J. J. Thomson and 

 Frank Horton). Second Edition. (Pp. viii+ 221, with 18 illustra- 

 tions.) (London : Longmans Green Co., 1921. Price 12s. 6d. net.) 

 This excellent monograph is so well known that it is hardly necessary to do 

 more than to draw attention to the publication of the new edition. The 

 work has been subjected to considerable revision. That the author has kept 

 it well abreast of current research is shown, for example, by the treatment 

 of the equilibrium space distribution of emulsoid particles in relation to their 

 electric charge, and the bearing of this on Perrin's classical experiments. It 

 is thus demonstrated that, whilst Perrin's conclusions are quite valid, they 

 apply only to a very limited range near the surface. Similarly, the chapter 

 on the coagulation of colloids gives a resume of the subject so far as it is 

 known and understood in the light of recent research work. 



The absolute necessity for a sound physical basis for colloid chemistry 

 is shown by the existence of such fundamental problems as the magnitude of 

 the coUoid electric charge, the equilibrium size of colloid particles, the quan- 

 titative formulation of the Brownian movement, the optical properties as a 

 function of the nature, size, and shape of the particles, the nature of the 

 Helmholtz double-layer, and other problems. 



It is only as progress is made in these fundamental quantities that we 

 can expect our knowledge of the manifold applications of colloid chemistry 

 to emerge from the empirical stage and to develop along rational lines. 



W. C. McC. Lewis. 



An Introduction to Biophysics. By David Burns, M.A., D.Sc. [Pp. xiii + 

 435. with 85 illustrations.] (London : J. & A. Churchill, 1921. Price 

 2 is. net.) 

 The object of this book, the author tells us, is to explain physical and physico- 

 chemical terminology and to deal with the physiology of vertebrates from the 

 point of view of the physical processes involved. 



To do this adequately would require a knowledge of physics which the 

 author evidently does not possess. His unit of force is " the dyne at 15° C." 

 or " the poundal at 59° F." Small wonder if, starting from such a definition, he 

 goes on to confuse, and even to equate to each other, force and kinetic energy, 

 thereby arriving at an entirely original mathematical relation between certain 

 properties of the molecules of a solid on the point of liquefaction. We next 

 learn that the vapour pressure of a liquid is equal to the gaseous pressure 

 above it, and in a later chapter we find Newton's law of cooling applied to 

 a problem in the conduction of heat. 



Not lack of material, but lack of space, makes us refrain from adding to 

 these instances of the author's inadequate grasp of the fundamentals of physics. 

 We should have been content to say less about them but that the author claims 

 to view the problems of life through a physicist's eyes and we wish to repudiate 

 the distorted picture. We welcome the book, nevertheless, as an admirable 

 refutation of the idea that physics, if it have the prefix " bio " added to it, 

 thereby becomes essentially a subject for a physiologist to teach. 



There is room for a subject which will correlate physics and physiology, 

 but it must come after and not instead of a grounding in physics itself, a 

 grounding so thorough that even the superstructure of biology will fail to 

 shake it. G. A. Sutherland. 



Les Theories d'Einstein Nouvelle ]Sdition Epuree, accrue de notes limi- 

 naires. By Lucien Fabre. [Pp. 255.] (Paris: Payot et Cie. 

 192 1. Price yf. 50.) 



In this small volume the author has presented an excellent account of 

 the development of the relativity conception in scientific thought, and of 



