24 Mr. J. Brown on the Electrification of the 



there was a slight haze of minute bubbles rising from the 

 zinc, which I thought might affect the result. 



5. To avoid this and to get a freer evolution of gas from 

 the platinum I platinized it, and clipped it to the end of a strip 

 of zinc 12 centimetres long by 1^ wide which was bent into a 

 flat spiral and amalgamated. Strong zinc -chloride solution 

 contained in a small beaker covered the zinc to about 3 mil- 

 limetres above its upper edge, and on this strong hydrochloric 

 acid was carefully poured with a specially constructed pipette, 

 so as to avoid as much as possible any mixture of the two 

 liquids. There was a moderate evolution of gas from the 

 platinum, none visible from the zinc. On connecting the 

 cell as before with the electrometer, the spot went to 350 in 

 four minutes, indicating the cell to be positive, and, by im- 

 plication, the issuing gas or vapour negative. 



6. There was not in any of the trials the slightest indication 

 of any positive electrification of the issuing gas, though it was 

 in two of them evolved in immediate contact with strong 

 hydrochloric acid. 



7. The same experiment was now repeated, using strong 

 zinc-sulphate solution surrounding the amalgamated zinc and 

 a 5-per-cent. solution of sulphuric acid in contact with the 

 platinum. Again the cell was positive from the first and the 

 spot went to 350 and off the scale in 9 minutes. 



8. When the zinc-platinum couple was immersed in acid 

 only, the sign of electrification of the cell varied according to 

 circumstances. It was positive (i. e. the issuing gas negative) 

 for both strong and dilute hydrochloric acid, except in two 

 cases with dilute acid when the zinc had been standing so as 

 to oxidize in the air, and evolved gas from itself. With 

 sulphuric acid the cell became quickly positive with a 5-per- 

 cent, solution, but slowly negative with a 10-per-cent. 

 solution. 



Although the results in this form of experiment are not 

 inconsistent with the hypothesis of § 3, the conditions seem 

 not sufficiently determinate or distinct to warrant any certain 

 conclusion beyond the obvious fact that here also negatively 

 electrified gas can be evolved from acid solutions without any 

 admixture of salt. 



9. It was felt, however, that the employment of a zinc- 

 platinum couple as an expression of the conditions stated in 

 § 3 was perhaps open to objection, and an endeavour was 

 made to get nearer the supposed conditions. A strip of zinc 

 was cleaned, bent into a spiral, and placed with its lower edge 

 in zinc-chloride solution on which was poured hydrochloric- 

 acid solution. This cell, however, became negative and 



