Electrification at Liquid-Gas Surfaces. 



369 



of the bubble diminished, approximating more and more 

 closely to the velocity it would have in the distilled water 

 used in the solution. The difference in velocity may be con- 

 siderable, and it is at once evident what large errors may be 

 introduced into such experiments on the cataphoresis o£ gas 

 bubbles by the presence or.' any contamination having a large 

 effect on the surface tension. 



In a study of the action of these organic substances on the 

 electrification of liquid-gas surfaces this disturbing effect 

 must be dealt with at the same time. The way in which 

 readings were taken is illustrated in the following table for 

 methyl alcohol. The solutions were not quite saturated with 

 air, so that a bubble, after being placed in the liquid, gradually 

 became absorbed. The concentrations are measured by 

 volume. 



In all the cases mentioned in this paper the charge was of 

 the same sign as in pure water, except, of course, when it 



was zero. 



Methyl alcohol and water. 



Concentrations. 



Diain. of 

 bubble. 



Time. 



Volts/cm. 



1/4 alcohol (25 per cent.). . . 

 1/8 „ 



•10 

 •04 



•14 

 10 

 •04 



•14 

 •12 

 •10 



•08 



•14 

 •12 

 •10 

 •06 



•14 

 •12 

 •08 

 •06 

 •04 



28 sees. 

 21 



21 

 17 

 14 



19 

 15 

 14 

 11 



16 

 14 

 12 

 11 



19 

 16 

 15 

 12 

 11 



10 



35 



1/16 „ 



1/32 „ 



1/64 „ 



Dist. water 



The successive solutions were made by removing each time 

 half the liquid in the cell and replacing it with the distilled 

 Phil Mag. S. 6. Vol. 28. No. 165 Sept. 1914. 2 B 



