Influence of Voltaic Currents on the Diffusion of Liquids. 65 



red liquid rose in narrow tube as if moving in same direction as the 

 current. Remarks. — Experiments Nos. 31 and 32 also show the diffi- 

 culty of producing definite lines in liquids which differ only in degree 

 of concentration. 



Exp. 33. — Now employed a current from twelve Grove's cells 

 arranged in single series, until Experiment No. 37. Small tabes 15 

 millims. high and 8 millims. bore. Lower liquid same as in last expe- 

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

 copious conduction. Deep curved line produced in tube beneath 

 cathode, and three distinct lines in the other tube, the middle one of 

 which merged itself into the upper one, and the two others remained. 

 The lines were not as definite as those produced by two liquids of 

 more widely differing chemical composition. 



Exp. 34. — Small tubes 17 millims. high, 5*5 millims. bore. Liquids 

 same as in last experiment. Copious conduction. A definite line 

 produced in colourless part of liquid in tube below cathode 1'75 millim. 

 above coloured portion, and a very faint one produced in the other 

 tube. These lines disappeared during the stoppage of current, and 

 reappeared whilst it was passing. They disappeared in about two or 

 three seconds and reappeared in about six seconds, and were the most 

 definite in the tube under cathode. This was verified several times. 



3. Experiments ivith Trehle Meniscus Apparatus. 



In the following experiment a different apparatus was used. A is 

 .& rectangular cell 20 centims. high, 12*5 centims. long, and 5' 5 centims. 

 wide, with front and back of polished plate glass, held together by 

 clamp screws. B and C are glass cups, fitted with lids and tubes as 

 the previously described apparatus (see p. 58), B having one tube and 

 C two (each tube being 15 millims. high and 12 millims. bore). D, 

 E, and F are three similar glass tubes, E and F being provided with 

 platinum electrodes, Gr and H. The cups were first filled with the 

 coloured liquid and placed in the cell, and the latter filled as in the 

 former apparatus. The object of the experiment was to compare the 

 effects of an up current and of a down current with ordinary diffusion 

 without current in the small tube within D. 



Exp. 35. — Lower liquid a saturated solution of cupric nitrate ; 

 upper one, 1 volume of nitric acid and 5 of water. A curved line was 

 -quickly produced in each of the two tubes, highest up in the one 

 under the anode ; that line remained in the colourless part of the 

 liquid whilst the one under the cathode descended or merged quickly 

 into the blue solution. The blue solution rose in height under the 

 cathode, as if the liquid moved in the same direction as the current. 

 Three permanent lines were produced in the tube under the cathode, 

 the top one slightly concave, the two lower ones straight. The line in 

 -colourless portion in the tube under anode rose slowly as the lower 



VOL. XXXII. f 



