Electrical Effects clae to Evaporation of Sodiitrn in Air, &c. 183 



Feh'uary 8, 1900. 



The LORD LISTER, F.R.C.S., D.C.L., President, in the Chair. 



A List of the Presents received was laid on the table, and thanks 

 ordered for them. 



The following Papers were read : — 



L "The Spectrum of a Aquilse." By Sir NoRMAN Lockyer, K.C.B., 

 F.R.S., and A. Fowler. 



IL " On the Production of Artificial Colour-blindness by Moonlight." 

 By G. J. BuRCH. Communicated by Professor GoTCH, F.R.S. 



in. " On the Relation of Artificial Colour-blindness to Successive Con- 

 trast." By G. J. BuRCH. Communicated by Professor GoTCH, 

 F.R.S. 



IV. " On Electrical Effects due to Evaporation of Sodium in Air and 

 other Gases." By W. Craig Henderson. Communicated by 

 Lord Kelvin, F.R.S. 



V. "On Electric Touch and the Molecular Changes produced in 

 Matter by Electric Waves." By Professor J. Chunder Bose. 

 Communicated by Lord Rayleigh, F.R.S. 



" On Electrical Effects due to Evaporation of Sodium in Air and 

 other Gases." By W. Craig Henderson, M.A., B.Sc, late 

 1851 Exhibition Science Scholar. Communicated by Lord 

 Kelvin, F.R.S. Received November 30, 1899,— Read Feb- 

 ruary 8, 1900. 



The experiments described below form part of a research which I 

 began in the summer of 1897 in the Cavendish Laboratory, Cam- 

 bridge, but was unable to complete before leaving Cambridge that 

 same year. The object of this part of the research, which was sug- 

 gested by Professor J. J. Thomson, was to determine whether evapora- 

 tion of an unelectrified liquid produces any electrification or not. 



The liquid used was fused sodium and the arrangement of apparatus 

 is shown in the accompanying drawing. 



The sodium to be fused was held in a vertical iron cylinder, A, 



Q 2 



