Electrification at Liquid- Gas Surfaces. 



371 



as high as 130 volts/cm. In one experiment, however, with 

 a 25 per cent, solution from which the excess of dissolved 

 gas had not been all removed, a number of very small spheres 

 — presumably of dissolved gas — collected on the axis of the 

 cell near the bubble under examination. These were observed 

 to move quite easily under 130 volts/cm., while the air-bubble 

 remained stationary. Out of curiosity small spheres of 

 benzine were tried in the same solution. These were found 

 io move while a bubble of air did not. 



The first three alcohols are miscible in all proportions with 

 water. Isobutyl alcohol is not, but dissolves in about 12 

 parts of water. In this case a saturated solution was made 

 to begin with, and readings were taken as in the other cases. 

 The conductivity of this solution was three times that of 

 water. 



Isobutyl alcohol and water. 





Cone. 



Diam. 



Time. 



Volts/cm. 



Time at 

 smallest size. 



Sat. soln. (8 %)?)... 

 1/2 sat 



•10 



68 sees. 



37 



24 



27 



21 



21 



19 



35 



19 sees. 



16 



23 



16 



12 



12 



11 



1/4 , 



1/8 „ 



1/16 „ 



]/32 



1/64 ., 



J/128 , 





The variation of velocity with the size was even more 

 marked in this case, and another column is given showing 

 the times when the bubble was at its smallest just before 

 vanishing as nearly as possible. The third reading in this 

 column is probably an accidental error. 



When more alcohol is added to the water than it will 

 dissolve two phases are formed — a heavier, rich in water, for 

 which readings are given above ; and a lighter, rich in 

 alcohol. In the former a bubble of air will move if it is 

 small enough. In the latter it could not be observed to 

 move under as much as 130 volts/cm. The conductivity of 

 this solution was less than 1 that of water. 



The velocity of a sphere of the lighter phase in the heavier 

 was observed. In this case also the heavier phase may not 

 be quite saturated with the lighter, and it is possible to begin 

 with a fairly large sphere and record its velocity for different 

 sizes till it disappears. Readings for such a case are given 

 here to show the effect. 



2B 2 



