586 Electrical Striations. [April 2, 



electric field in the part near the cathode side of the bright head of a 

 striation — the dark part — is weak ; here the ions have not got the 

 minimum amount of energy requisite for them to be luminous when 

 they recombine ; in the bright part of the striation the electric field 

 is strong, and here the ions get sufficient kinetic energy to enable 

 them to give out light when they combine. If the energy required 

 for an ion to give out visible light is greater for light at the blue end 

 of the spectrum than at the red, we might get blue light at one part 

 of the striation, red at another, an effect often observed when we 

 have a mixture of mercury vapour and hydrogen in the tube ; a simi- 

 lar separation of the spectra of the two gases in a striation might 

 also be produced if one of the gases were more easily ionized than the 

 other. 



I wish to thank my assistant, Mr. Everett, for the assistance he 

 has given me in these investigations. 



GENERAL MONTHLY MEETING, 



Monday, April 5, 1909. 



His Grace The Duke of Northumberland, K.G. D.C.L. F.R.S., 

 President, in the Chair. 



Laurence J. Baker, Esq., J. P. 

 Mrs. S. G. Brown, 

 Miss Carvill, 



were elected Members of the Royal Institution. 



The Special Thanks of the Members were returned to Hugo 

 Miiller, Esq., Ph.D. LL.D. F.R.S., for his Donation of £100 to the 

 Fund for the Promotion of Experimental Research at Low Tem- 

 peratures. 



The Honorary Secretary reported. That the Managers had, at 

 their Meeting held this day, elected Sir James Dewar, M.A. LL.D. 

 D.Sc. F.R.S., Fullerian Professor of Chemistry for a period of 

 three years. 



The Presents received since the last Meeting were laid on the 

 table, and the thanks of the Members returned for the same, viz. : — 



