T H E 

 LONDON, EDINBURGH, and DUBLIN 



PHILOSOPHICAL MAGAZINE 



AND 



JOURNAL OP SCIENCE. 



[FIFTH SERIES.] 



OCTOBER 1893. 



XXXI. On the Effect of Electrification and Chemical Action 

 on a Steam-Jet, and of Water- Vapour on the Discharge of 

 Electricity through Gases. By J. J. Thomson, M.A., 

 F.R.S., Cavendish Professor of Experimental Physics, 

 Cambridge* . 



THE investigations of R. v. Helmholtzf, R. v. Helm- 

 holtz and Richarz X, Shelford Bidwell§, and Aitken ||, 

 on the effects of electrification and of chemical action on the 

 condensation of steam in a steam-jet have brought to light facts 

 which are so striking and suggestive that it seems desirable to 

 consider what, according to the principles which are known to 

 govern the condensation of steam, would be the effect of 

 electrification on the steam-jet, and how far these principles 

 will go in explaining the phenomena observed by the above- 

 mentioned physicists. 



Before considering the effect of electrification in increasing 

 the number of water-drops condensed in the jet, it is advisable 

 to consider the effect of the surface-tension of the water-drop, 

 as this is one of the most formidable obstacles in the way of 

 the condensation of the drops. 



The pressure of the water-vapour in equilibrium over a 

 spherical drop of water is, as was first shown by Lord Kelvin, 



* Communicated by the Author. 



f R. v. Heltuholtz, Wied. Ann. xxxii. p. 1 (1887). 



i R. v. Helmholtz & Richarz, Wied. Ann. xl. p. 161 (1890). 



§ Bidwell, Phil. Mag. [5] xxix. p. 158 (1890). 



!| Aitken, Proc. Roy. tioc. li. p. 408 (1892). 



Phil. Mag. S. 5. Vol. 36. No. 221. Oct. 1893. Y 



