Influence of Voltaic Currents on the Diffusion of Liquids. 61 



tive meniscus became diffused, and the positive one a distinct line ; 

 the solution was of a lighter colour 3*0 millims. below the latter 

 meniscus than lower down. Several reversals of the current reversed 

 these effects each time in a few minutes, the period requisite increasing 

 each time. 



Exp. 12. — Same tubes as in Experiments 5 to 11. Lower liquid a 

 saturated solution of cupric nitrate ; upper one dilute hydrochloric 

 acid 1 volume to 8 of water. Copious conduction. Coloured liquid 

 below anode seemed to sink. A definite line appeared at positive 

 meniscus in one and a half minute. By reversal of current that line 

 became indefinite almost at once, and a definite one appeared at the 

 other surface of contact in two and a half minutes. The mass of 

 lower solution appeared to move in the direction of the current. 



Exp. 13. — Tubes 15 millims. long and 7"5 millims. bore. Lower 

 liquid same as in last experiment ; upper one, 2 ozs. potassic bromide 

 dissolved in 12 ozs. water. Each contact surface of the lower liquid 

 became green previous to passage of current. Conduction moderate. 

 Green colour extended downwards at surface below anode, and did not 

 decrease at the other meniscus. Definite lines were produced at 

 both meiiiscuses, the negative meniscus also became bluish. Reversed 

 current, a definite line was produced in an extremely dilute part of 

 lower solution below cathode ; the other appearances were also 

 reversed. 



Fig. 2. 



CoIolltLcss — 



Pate cjreen, 



Dirty cjrzax^ aLrruost blacl 



BLjlc 



Exp. 14. — Lower liquid the same as in the last experiment ; upper 

 one dilute nitric acid 1 in 10. Two definite horizontal lines formed in 

 the lower liquid below cathode in about one minute, about 1*75 millim. 

 asunder, with a pale yellow stratum of liquid beneath them, and soon 

 merged into each other. The other meniscus sank and became diffuse. 



Exp. 15. — Lower liquid a strong green solution of cupric bromide ; 

 upper one same as in last experiment. Upper surfaces of lower solu- 

 tion were convex and became blue without the aid of the current. 

 Copious conduction. Blueness of surface disappeared from negative 

 meniscus and increased to positive one, and became deeper in colour 

 to 1*75 millim. thick. Definite line at surface below cathode, and 

 diffused meniscus below anode. Negative meniscus became strongly 



