Chemistry and Physics. 463 



The present issue has been revised and the part dealing with the 

 detection of the acids has been made more systematic. The book 

 contains a concise statement of the ionic theory, with illustrations 

 of its application to qualitative analysis. h. l. w. 



8. Die heterogenen Gleichgewichte vom Standpunkte der Pha- 

 senlehre ; von Dr. H. W. Bakhuis Roozeboom. Vol. I, pp. 216, 

 8vo. Braunschweig. 1901. (Friedrich Vieweg & Sohn.) — The 

 introduction to this volume is devoted to a discussion of the 

 Gibbs' phase rule with a few general applications to cases of 

 equilibrium. Book I deals very systematically and thoroughly 

 with equilibrium in systems containing one component. Volumes 

 II and III are to be devoted to systems of two and three com- 

 ponents, respectively. 



Roozeboom, in 1887, was, the first to apply the phase rule to 

 chemistry and since then he has contributed perhaps more than 

 anyone else to our knowledge of chemical equilibrium. The 

 book can be most heartily recommended as giving a thorough 

 presentation of the subject. h. w. f. 



9. Viscosity of Helium. — Lord Rayleigh found for the vis- 

 cosity of pure helium, between 15° and 100°, the value h = 0*681 

 and C (Sutherland) = 72-2. H. Schultze, who has also worked 

 on the viscosity of argon, has redetermined the viscosity of 

 helium, but regrets that the helium used by him was not per- 

 fectly pure. He, therefore, compares his results with that found 

 by Rayleigh for helium not wholly pure. The latter found in 

 this case h = 0*96. Schultze finds h = 1*086 at 15°. He calls 

 attention to a new and unexplained phenomenon in the transpira- 

 tion of gases. He often found a difference of over 1 per cent in 

 the results of the measurement of the viscosity of a mixture of 

 gases — such as helium and neon or argon — and these differences 

 arose from a change in direction of the transpiration of the gases 

 through the capillary tube. The author does not agree with O. 

 E. Meyer in attributing the phenomenon to the character of the 

 capillary tubes. — Ami. der Physik, No. 10, 1901, pp. 302-314. 



J. t. 



10.' Air-tight glass stop-cocks. — All who have worked in sub- 

 jects requiring high exhaustions have met with difficulty in 

 obtaining air-tight stop-cocks. The most perfectly ground glass 

 stop-cocks will leak after a few hours. This leaking is hastened 

 by the presence of high tension electrical apparatus, and in this 

 case is apparently due to minute paths formed by electrification 

 on the surface of the stop-cock. Hermann Thiele and Moritz 

 Eckardt describes a mercury seal for a stop-cock which prevents 

 to a high degree the leaking of the cock. They also describe a 

 mercury seal which dispenses with a stop-cock. — Ann. der Physik., 

 No. 10, 1901, pp. 428-431. j. t. 



11. Migration of the ions. — Hittorf has shown the dependence 

 of this migration upon the concentration and the temperature 

 of the solution of the electrolyte. R. Gans investigates the 

 dependence of this migration upon physical conditions and finds 



