182 Proceedings of Royal Society of Edinburgh. [sess. 
short circuited over night. Next day, the electromotive force of 
cell was 0-0041 Y. The changes which took place when the 
electrodes were charged with hydrogen are given below in tabular 
form, — the electromotive force, except when otherwise stated, 
being measured a minute or two after the charging current was 
interrupted. 
Hydrogen contained in 
E. M. F. 
Potential against Zw in Zn S0 4 . 
£ 
P 
&P 
£ 
p • 
0’0 c.c. 
0T2 „ 
99 99 
5-18 „ 
14*18 ,, 
0"0 c.c. 
o-o ,, 
1*08 ,, 
9 9 9 9 
99 9 9 
0-0041 YjS- 
0-8287 ,, 
0-0029 p- 
0-0053 0- 
0-0469 ,, 
1-5904 Y. 
0'7686 ,, 
0 -7677 s, 
0-7684 „ 
1-5954 Y. 
1-5963 „ 
0-7665 ,, 
07743 „ 
After 6 minutes. 
„ io „ 
„ 25 „ 
„ 40 „ 
„ 100 „ 
,, 18 hours. 
0*0352 ,, 
0-0293 „ 
0-0205 ,, 
0-0176 „ 
0-0147 „ 
0-0071 „ 
: : : : : 
w 
O 
0-7798 „ 
When j3 was supersaturated with hydrogen with a current 
strength of 0-025 amp., the electromotive force of the cell ftp was 
0T001 Y., hut this gradually diminished during the course of 
time, and approximated to zero. "With a higher current strength, 
viz., 0"3 amp., the electromotive force after some seconds was 
0*1278 V., and this also gradually fell off. Finally, when both 
electrodes were supersaturated with hydrogen, and the excess of 
the gas allowed to come off, the electromotive force was 0’0029 Y. 1 
In considering the results contained in the above table, we 
ought to pay special attention to the cell containing 14*18 c.c. 
hydrogen in the electrode /3 and 1*08 c.c. in p, since in this 
case the gradual diminution of the electromotive force has been 
measured. In other cells the same effect was noted at other 
concentrations. Intermediate measurements were dispensed with 
in this instance, however, in order to study particularly a cell con- 
taining a considerable difference in concentration of the hydrogen 
in the two electrodes. 
