<52 Mr. J. "W. SAvan. On some Voltaic Combinations [May 24, 



and at other times the chlorine forming a nearly complete envelope 

 round the carbon, these conditions following in rapid alternation. 

 The highest E.M.F. observed was 1'25 volt. The largest current given 

 was 0'9 ampere with a P.D. of 0'25 volt. The current was fluctuat- 

 ing, owing to the varying conditions at the carbon pole. 



Exp. 5. The following figure shows a construction almost identical 

 with the last, differing only in a few practical details, occasioned by 

 this cell being made larger than the last. The porcelain tube pre- 

 viously used was replaced by an inverted porcelain crucible, having 

 two holes drilled in the bottom ; the larger hole afforded a passage 

 for the conductor from the carbon pole : through the smaller one 

 there passed a porcelain pipe for the chlorine supply. The carbon 

 pole was composed of a disc of gas retort carbon, pierced with holes, 

 as shown in the figure. In the middle of the disc was screwed a tube 

 of carbon, which passed up through the larger hole in the bottom of 

 the crucible and was secured in this position by nuts of retort carbon. 

 The bottom of the carbon tube was filled with fused lead, into which 

 dipped a thick copper wire that formed the positive pole connexion. 



FIGK 6. 



The connexions between the carbon and porcelain were luted with a 

 mixture of borax and fire-clay fused at a bright red heat. The other 

 vessel consisted of a short cylindrical plumbago crucible. The fused 

 lead was, as usual, on the bottom, connexion being made with it by 

 means of a heavy open iron ring, with its free end turned up and bent 

 over the rim of the crucible. The internal resistance was small, 

 owing to the improved contact of the leading wire with the carbon 



