422 Mr. S. H. Burbury on the Work ivliich may 



a homogeneous beam of secondary arrays may not be strictly 

 homogeneous, for a little consideration will show that the 

 method is not a very sensitive one for detecting the different 

 constituents. It is certain, however, that the secondary 

 beams from certain substances are remarkably homogeneous 

 in comparison with the primary. 



A fuller discussion of some of the experimental results 

 briefly referred to in this paper will be given in a paper 

 dealing more exclusively with the theory of secondary rays 

 when experiments which we are now engaged upon have 

 been completed. 



Note, Aug. 21, 1907. — Parker and Sexton have recently 

 announced (' Nature, 5 Aug. 1, 1907) that, acting upon the 

 suggestion of Pi of. J. J. Thomson that the accepted atomic 

 weight of cobalt was too high, they have determined it electro- 

 lytically, and have obtained as the mean of fifteen deter- 

 minations the value 57*7. At the time that the suggestion 

 was made by Prof. Thomson only a short preliminary notice 

 of these results had been published, so that the published 

 evidence was insufficient to distinguish between the possi- 

 bilities of cobalt or nickel being wrongly placed. It must, 

 however, be concluded that the first two series of experiments 

 described in this paper point very markedly to the probability 

 of the accepted atomic weight of nickel as being much too low. 

 The value 59 has consequently been accepted for cobalt. (See 

 figs. 3 and 4.) 



XXXVIII. On the Work which may be gained during the 

 Mixture of Gases. By S. H. Burbury, F.B.S.* 



IN reference to my paper in the July number of this 

 Magazine, Lord Rayleigh calls my attention to a paper 

 of his in Phil Mag. ser. 4, \ol. xlix. (1875) p. 311, with the 

 above title. He there seeks to prove the law enunciated on 

 p. 125 of Professor Bryan's recent work. 



The problem may be stated thus : — In a horizontal tube is 

 a mixture of two gases, say oxygen and hydrogen, the pressure 

 of the combined gases, and also the temperature, being uniform 

 throughout the tube. Consistently with these conditions the 

 gases may be (1) mixed in the same relative proportions at all 

 points in. the tube, or (2) wholly or partially separated, oxygen 

 being in greater relative density towards one end, hydrogen 

 towards the other. 



Rayleigh and Bryan maintain that to bring the mixture 



* Communicated by the Author. 



