Influence of Voltaic Currents on the Diffusion of Liquids. 7& 



liquid. On stopping the current the convex line ceased and the 

 meniscus was flat. By again reversing the current and sending it 

 down the tube, the liquid descended at once, and two lines were 

 formed, one in the colourless liquid, and the other at the edge of the 

 blue ; wavy and falling appearances also occurred again. A layer of 

 liquid of deep blue colour formed upon and above the meniscus. 

 Remarks. — I have not found the cause of the reversal of the movement 

 of the meniscus in Experiments Nos. 41, 42, and 43. 



Exp. 4i4t. — Inner liquid, 1 volume of saturated solution of sodic 

 carbonate and 3 volumes of water (sp. gr. 1'09). Outer one, a strong 

 solution of ammonic nitrate, slightly acid (sp. gr. 1*19). Current sent 

 up the tube. Conduction very moderate. Definite line produced. 

 The meniscus did not ascend or descend. A layer of red colour was 

 produced in the lowest layer of blue liquid, and around that liquid, 

 showing that the acid set free above the meniscus from the electrolysis 

 of the liquid ascended by capillary action between the blue liquid and 

 the tube. Stopped the current ; no such change occurred. Reversed 

 its direction (i.e. sent it down the tube). The blue colour became 

 strongly curved with its convexity downwards, the layer of red liquid 

 gradually disappeared, and the meniscus slightly descended in the 

 direction of the current. A wavy appearance of the colourless liquid 

 close to meniscus and streaming of it downwards was produced, as in 

 a previous experiment, as if a heavier liquid was set free at the under 

 surface of the meniscus by electrolysis of the outer solution. 



Remarks. — The results of these experiments with the single tube 

 apparatus, may (most of them) be explained in a similar manner (see 

 p. 67, et sea.) to the previous ones. They also show that the move- 

 ments of the meniscus, up or down, depend upon the particular com- 

 bination of liquids employed, as well as upon the direction of the 

 current : for instance, in Experiment No. 44, no such movement took 

 place ; whilst in Experiments Nos. 40, 41, 42, and 43, it occurred 

 freely. The comparatively quick movements of the meniscus in these- 

 latter experiments and the circumstances that the contiguous liquid 

 surfaces appear to act as electrodes, favour the view that the movement 

 is partly a result of pressure, and that a somewhat similar movement by 

 the influence of an electric current, takes place to a small extent with 

 miscible liquids in glass tubes as occurs with immiscible ones (such as- 

 mercury and an aqueous solution) in a capillary electroscope. 



5. Transfer of the Mass of Solution. 



All the foregoing experiments show that the apparent movement of 

 mass and production of definite lines, is not confined to capillary 

 tubes. With the double meniscus apparatus, the lower liquid ap- 

 peared to move in the direction of the current in Experiments Nos. 2, 

 12, 18, 19, 21 (25), 29, 32, and 35 ; and in the opposite direction in 



