400 BEPORT — 1886. 



January 7. — Experiment with all four tubes in multiple arc, two of them dip- 

 ping into the same pair of vessels ; the solutions of BaCl^ and Na2S04 weaker than 

 before, viz., sp. gr. 1-050, because in the cold weather the sulphate of soda was apt 

 to crystaUise out of the old solutions. Current started at 5 p.m., 20 cells. By 

 January 9, 9 a.m., rings were formed in tubes II., III., and IV. No ring in V., but 

 some air-bubbles had collected in it, and apparently stopped its current. The rings 

 in LI, and IV. were beautifully sharp. 



Distance of ring from Na„SO. end 17-0 6-5 16-9 



68-7 80-8 68-5 



Januaj-y 9. — Another similar experiment but with 15 cells. By the morning 

 of January 11 rings were formed in 3 tubes, and one was forming in tube V. 



II. III. IV. V. 



Distance from Na„SO, end 26-5 10-4 21-0 33-7 



BaCl^end 59-2 769 64-4 526 



January 22.— A precisely similar experiment, except that 20 cells were applied.. 

 By January 23 (evening) rings were forming in three of the tubes, but there waa 

 an air-bubble again in V. 



Distance of ring from Na.SO^ end 34-3 22-3 24-4 



„ BaCUend 51-4 65-0 61-0 



Feh-uary 1. — Similar experiment. 



^ II. III. 



Distance from Na^SO^ end 382 30-6 



„ BaOi, end 47-5 567 



'2 



So far the data are not satisfactory. There is a decided consensus in favour 

 of the more rapid travelling of Ba than of SO4, but no estimate of the ratio of 

 the velocities can be relied on. The average makes Ba travel 3-2 times as fast as 

 SO^ (see p. 394). 



Experiments on jelly-JiUed tuhes. 



Four new tube.s were made of dimensions and numbers here specified : — 

 Number VI. VII. VHI. IX. 



Length 86-6 88-3 84-8 103-8 centims. 



Diameter -327 -460 -476 -825 „ 



A gelatine solution was made by dissolving 20 grammes of gelatine in 150 cc. 

 of dilute acetic acid of ordinarv testing strength, viz., 1 centigramme molecule per 

 5 cc, the tubes filled and allowed to go solid. The tubes were arranged in multiple 

 arc with a galvanometer able to be switched at pleasure into the circuit of each. 

 The solutions in the vessels were BaCU and Na^SO^, as before, 



February 13. — The E.M.F. of 24 cells was applied to these four new tubes at 

 noon, and readings of the current (which was very weak) taken at intervals. 



It was found that something in travelling from the anode vessel (presumably the 

 Ba) rendered the jelly turbid, and that the turbidity, being sharply defined, served as 

 an indication of the distance to which this ion had reached. Marks were accordingly 

 made on the tube to fix its position at different times, the distances of these marks 

 from the end of the tube bemg afterwards measured. After a time the SO^, travelling 

 from the other end, met the Ba and precipitated a sharp rmg of BaSO^, whose position 

 was noted. The current was not stopped, however; it was left on to see at what rate 

 the precipitation advanced, and whether it advanced in both directions or in only 

 one. In the free liquid HCl tubes it had seemed only to advance in the direction 

 opposed to the current, viz., towards the BaCl.^ vessel. It was now observed in 

 these jelly tubes to widen out both ways, but faster towards the BaCU vessel than 



towards the Na2S0^. c/-w • j- 



It was specially noticeable that in these jelly tubes the disc of BaSO^, indicating 

 the meeting of the ions, formed near the middle of the tube, instead of much 

 nearer the Na^SO^ end, as it had done in free liquid. Thus while Ba travelled 41-1 cm. 



