46o SCIENCE PROGRESS 



or actually to abstract this information and supply it properly arranged to 

 the inquirer. Specimen queries are given in the pamphlet relating to the 

 Bureau, and from them it is clear that the ground it is prepared to cover is 

 not limited to the collection of facts, but extends to such things as the loca- 

 tion of foreign patents and advice concerning the availability of research funds. 

 The Bureau is managed by an influential executive council and makes no 

 charge for its services except in cases where special search has to be made. 

 With a capable and energetic staff it is obvious that a service of this kind 

 might give most valuable help to everyone engaged in scientific work, and 

 one cannot help envying the country possessing it. 



The Fourth Report of the British Association Committee on Colloid 

 Chemistry and its General and Industrial Applications has now been published 

 by the Department of Scientific and Industrial Research (pp. 382, paper 

 covers, H.M. Stationery Office, price 5s. 6d. net). It contains a number of 

 academic and technical papers of great value and interest. Among them are 

 two most important papers by Mr. E. Edser, the well-known writer of physics 

 textbooks. The first deals with the physical properties of liquids, and con- 

 tains an extension of Laplace's theory of capillarity. Assuming that two mole- 

 cules attract each other with a force varying as the inverse nth power of 

 thdir distance apart, it is shown that, for liquids to possess cohesion, n must 

 be greater than 4, and that, for surface tension to exist, it must be greater 

 than 5. Substituting data obtained experimentally in the theoretical equa- 

 tions it is found that, for all liquids except mercury (including the liquefied 

 " permanent " gases), n is equal to 8. The evidence in favour of this inverse 

 eighth power law is very strong, and it is not improbable that the final 

 solution to the hundred-year-old problem of the precise law of molecular 

 attraction has at last been attained. In the course of his arguments Edser 

 establishes a number of interesting formulae, e.g. that the surface tension s 

 of a liquid at a temperature T°K is given by Vs = A(p— p') (i — -yT*) where 

 p and p' are the densities of the liquid and its vapour, and A and y constants, 

 the latter approximately equal to JT"*. He also provides a theoretical 

 basis for Trouton's Latent Heat rule, Walden's rule, and the formula of 

 Eotvos. Among the numerical calculations given by the author is one 

 which gives a surprising result for the rate of escape and return of the mole- 

 cules of a liquid in equilibrium with its vapour. Thus for benzene at 20° C, 

 the number of molecules returning to the surface per second is suf&cient to 

 renew the top layer of molecules 35,000,000 times during that period I The 

 second paper is directly concerned with the physical aspects of the Flotation 

 process for the concentration of minerals, and contains a discussion of such 

 matters as contact angles, flocculation, and frothing. Among the other 

 contents of the report are papers on "Membrane Equilibria," by W. E. Garner ; 

 "Lubrication," W. B. Hard}'; and " Disperse Systems in Gases," by W. E. 

 Gibbs, of the Salt Union Co., Ltd., the latter containing a comprehensive and 

 most interesting account of our knowledge of vapour, dust, and smoke clouds. 

 The report appears to us to be one of the most important documents compiled 

 by a B.A. Committee, and the Department of Scientific and Industrial 

 Research is to be congratulated on having provided the financial help which 

 was essential for its publication. 



Inquiries having been received regarding the Nobel Medical Prize, we 

 have made inquiries and find that it was not distributed! at all for the years 

 1 91 5. 1 91 6, 1 91 7, 1918, 1 92 1, and for this year. 



