Influence of Voltaic Currents on the Diffusion of Liquids. 67 



violence of the action caused the liquids to mix, and required the ex- 

 periment to be stopped. The current was too strong for the persistent 

 production of definite lines. 



Exp. 37. — Same tubes. Lower liquid, 1 volume of sulphuric acid 

 and 2 of water ; upper one, 1 volume of nitric acid and 5 of water. 

 Very copious conduction. A line with convexity downwards was 

 immediately produced at each meniscus, and was soon followed by a 

 strong action at each surface, strongest at the positive one, causing a 

 streaming upwards of the lower liquid as if unequally heated, and a 

 down rushing of the upper liquid, which destroyed the definite line. 

 Small bubbles of gas or vapour were also produced all over the surface 

 of the positive meniscus only. 



Exp. 38. — Meniscus tubes 22 millims. high and 12 millims. wide. 

 Lower liquid a mixture of 2 measures of saturated solution of cupric 

 sulphate and 1 measure of dilute sulphuric acid, consisting of 1 volume 

 of acid to 2J volumes of water ; upper liquid, 1 volume of sulphuric 

 acid and 7 of water. Two lines were produced at the negative 

 meniscus. The violence of the action soon put a stop to the experi- 

 ment. Remarks. — The stronger action at the positive meniscus than at 

 the negative one in Experiments 37 and 38 was probably due to the 

 more definite accumulation of acid and basic products in contiguous 

 layers at the former than at the latter meniscus. 



Exp. 39. — Meniscus tubes, 17 millims. high and 8 millims. bore. 

 Lower liquid, 1 volume of nitric acid and 1 volume of water ; upper one, 

 1 volume of nitric acid and 5 of water. Conduction copious. A line 

 with convexity downwards produced at once above positive meniscus, 

 followed soon by one above negative meniscus ; this was succeeded by 

 strong wavy movements at those surfaces, as if the effect of heat or 

 of liquids of different specific gravity. 



Remarks on the Foregoing Experiments. 



The phenomena in all the experiments are evidently very complex, 

 and are a mixture of physical and chemical effects. The effects to be 

 explained consist chiefly of the production of the fine lines, and an 

 apparent movement of the mass of the liquid. The hypothesis which 

 seems to be the most completely consistent with them is, that 

 they are chiefly due to electrolytic changes, to differences of specific 

 gravity, to ordinary liquid diffusion, to electric transfer and diffu- 

 sion of liquids, and to heat of electric conduction resistance. That 

 also the surfaces of mutual contact of the two solutions, and of 

 those solutions with the layers of liquid produced by electrolysis, 

 act in some degree as electrodes and as diffusion diaphragms. 

 That by the electrolytic liberation and subsequent accumulation of 

 electropositive and electronegative ingredients, and the transference 

 of water by electric diffusion and its accumulation on the sides of the 



p2 



