370 



Mr. H. A. McTaggart on 



water used. This method was found to give more consistent 

 results than could be got by mixing each solution separately, 

 though the concentrations are not so evenly distributed. In 

 any case it is extremely difficult to get regular results showing 

 the effect of the concentration of the alcohol on the velocity, 

 i. e., on the charge. From this list the times for bubbles of the 

 same size, as nearly as possible, — (*1 mm.) — are selected and 

 plotted in a curve against the concentration. This method 

 will show at least the general shape of the curve. A similar 

 series of readings was taken for each alcohol, and the selected 

 lists are given all for bubbles as near the same size as 

 possible. In every case the bubble carried the same sign of 

 charge — negative — as it would in pure water. 



Ethyl alcohol and water. 



Cone. 



Diam. 



Time. 



Yolts/cm. 



1/4 alcohol 



•10 



42 sees. 



21 



15 



17 



15 



13 



16 



16 



11 



35 



1/8 „ 



1/16 „ 



1/32 „ 



1/64 „ 



1/128 „ 



1/256 ., 



1/512 „ 



„ 





In this table the times do not decrease uniformly — an 

 irregularity possibly due to the difficulty in keeping the 

 pipette used for making the bubbles free from contamination. 



Propyl alcohol and water. 



Cone. 



Diam. 



Time. 



Volts/cm. 



1/4 alcohol 



•10 



No motion. 

 28 sees. 

 20 

 17 

 15 

 15 

 16 

 16 

 14 

 11 



35 



1/8 „ 



1/16 „ 



1/32 „ 



1/64 „ 



1/128 „ 



1/256 „ 



1/512 „ 



1/1024 „ 



Water 





In solutions containing 25 per cent, or more of this alcohol, 

 no motion of an air-bubble could be observed under potentials 



