198 Notices respecting New Boohs. 



everyday life, such as the rising of cream and the churning of 

 milk, precipitation of river-sludge and sewage, sizing and 

 colouring of paper with mixed dyes, the part played by ad- 

 sorption in the fertility of soils, and the recently discovered and 

 very remarkable electro-osmosis phenomena with their industrial 

 applications. 



The last chapter is devoted to Langmuir's work on evaporation 

 and condensation, the rate of adsorption of gases by solids, the 

 kinetics of heterogeneous reactions, and the chemical theory of 

 surface forces, with the extremely interesting conceptions of the 

 orientation of the molecules on the surfaces of liquids, in benzene 

 for example the molecules arranging themselves so that the benzene 

 rings lie flat upon the surface. In connexion with the subject of 

 evaporation and condensation as treated in this chapter it may be 

 of interest to draw attention to a recent paper on the subject pub- 

 lished in this journal*, dealing with the discovery of a sort of 

 critical temperature for each element below which the element 

 condenses as a heterogeneous non-crystalline film, and above 

 which it deposits in a granular crystalline form. The critical 

 temperature is surprising low, — 90° 0. for cadmium, and — 140° C. 

 for mercury, for example. 



The new material in Volume II. deals with the subject of 

 osmotic pressure and the theory of dilute solutions, and vegetable 

 tanning is taken up in connexion with adsorption and membrane 

 equilibria. 



Volume III. will treat the whole subject from the Quantum 

 standpoint. 



The treatise as a whole is not only the most complete, up-to-date 

 and best text-book on physical chemistry that I have ever read, 

 but, in addition, one of the most interesting scientific books that 

 has come to my notice in many years. 



E. W. Wood, Paris, April 1919. 



Osmotic Pressure. By Alexander Eikdlay. Second Edition. 

 Longmans, Green & Co. Price 6s. net. 



This little monograph gives a concise account of the experimental 

 work and speculations on the subject in question. With respect 

 to the various theories of the nature and cause of osmosis it 

 preserves an impartial tone, stating the views of the various 

 authors without pronouncing very decidedly in favour of any 

 particular school. This second edition gives an account of the 

 apparatus employed by Morse for his measurements of large 

 osmotic pressures which is fuller in detail than that of the first 

 edition, and brings the subject up to date by adding a description 

 of the new work carried out during the past six years. The 



* R. W. "wood, " Condensation and Refraction of Gas Molecules," 

 Phil. Mas-. October 1916. 



