78 



Dr. G. Gore. 



single cell of copper and platinum in dilute sulphuric acid, and from 

 a single series of twelve Grove's elements. The electrodes were of 

 platinum, and the capillary tube was capable of being raised or 

 lowered through very minute distances by means of the rack and 

 pinion. Tubes of various internal diameters were used, varying from 

 1% *6, '45, to "35 millim. The only pair of solutions employed con- 

 sisted of a one-fourth saturated solution of potassic chloride as the 

 lighter liquid, and a saturated one of sodic sulphate as the heavier one 

 (as in Experiment No. 40). The currents were only continued during" 

 periods of less than half a minute at the utmost. 



With a tube 1 millim. diameter, and the electric current from either 

 source, or in either direction, no movement of the meniscus was visible. 

 With a tube *6 millim. diameter, or with one '45 millim. diameter, 

 either an upward current or a downward one from the twelve cells 

 caused a downward motion of the meniscus, strongest with the upward 

 current. The motion was more rapid than in the experiments with, 

 the usual wider meniscus tubes of this research, and less rapid than 

 with mercury in a capillary electroscope ; it appeared to be due partly 

 to heat of conduction resistance (producing expansion) and partly to 

 electric convection. (N.B. — Electric osmose would have produced a 

 more rapid movement of the meniscus upward by a downward current, 

 than of downward movement by an upward one.) Solid particles 

 suspended in the liquid were accelerated in their velocity of falling by 

 the passage of the current. The meniscus did not continue very 

 definite, and no lines (if any existed) were sufficiently distinct to be 

 perceived. The meniscus also showed no return movement on stop- 

 ping the current. (In this respect it differed from the movement 

 with mercury, &c.) I could not ascertain that the meniscus influenced 

 the motion ; the latter continued the same when the meniscus was at 

 the extreme end of the tube as when it was within it. It is pro- 

 bable that the movements were to some extent of the same kind as 

 those observed by Armstrong, Quincke, and Jiirgensen (see p. 74), 

 and would have occurred with one liquid alone. The current from 

 the single cell had either no effect, or else a barely perceptible one 

 similar to that produced by the one from the Grove's battery. With 

 a tube *35 millim. bore, a very slight downward movement was pro- 

 duced by the upward current from the battery. The downward 

 current had the same effect, but in a less degree. No effect was 

 observed with the current from the single cell. 



From the comparative slowness of the movement and the great 

 strength of electric current necessary to produce it, I consider that 

 nearly the whole of the movement of two miscible liquids in capillary 

 tubes is very different from that occurring with mercury and solution 

 in such tubes. The tubes, however, used with mercury are usually of 

 much smaller diameter. 



