1898-99.] Dr H. Marshall on Polarisation Phenomena. 
53 1 
with the large basins, although the volume was only about one- 
seventh. Three-quarters of a gram each of ammonium sulphate 
and ammonia were added, and a current of 0T6 to 0T8 ampere 
employed. 
Duplicate determinations carried out in the two ways, with the 
same quantity of nickel, showed that deposition was always com- 
pleted sooner in the smaller vessel, despite the feebler current, 
while the completion was indicated more clearly on account of the 
greater rapidity with which the rise of potential took place. The 
following results were obtained with about 0’17 gm. of nickel 
ammonium sulphate in each case, corresponding to about 25 mg. 
of nickel. 
Small vessel, 18 c.c. Large basin, 135 c.c. 
Time 
Volt. 
Amp. 
Time. 
Volt. 
Amp. 
h.m. 
h.m. 
0.0 
2-85 
0*15 
IX. 0.0 
3*1 
0-60 
0.30 
2-95 
•15 
0.30 
3*15 
•58 
0.45 
3*0 
•15 
0.45 
3-15 
•58 
1.0 
3-1 
•15 
1.0 
3*15 
•58 
1.15 
3-3 
•14 
1.30 
3-2 
•58 
1.30 
3’4 
•14 
1.45 
3*25 
•58 
2.0 
3-3 
•57 
2.15 
3-4 
•57 
0.0 
3-0 
0-17 
X. 0.0 
3-05 
0-65 
0.20 
3*0 
*17 
1.0 
3*15 
•68 
0.50 
3-1 
•17 
2.10 
3*35 
•68 
1.10 
3*3 
•17 
2.30 
3-5 
•66 
1.25 
3-4 
*17 
2.40 
3*6 
•65 
1.30 
3*5 
•16 
Experiments similar to Y. and VI., but with the smaller vessels, 
further showed that the actual quantity of nickel involved in 
causing the change is less than with the larger volume of solution • 
as was to be expected, it is the strength of solution which deter- 
mines the effect, so that when the rise of potential sets in with an 
experiment on the smaller scale the quantity of nickel still to be 
deposited is only a fraction of what it is in the large apparatus. 
This is shown by the following results : — 
XI. 
Volume of Solution, 18 c.c. 
Mckel added. Volt. Amp. 
0* 3-55 0-16 
0*45 m.g. 3-10 *18 
0- 9 3*05 *18 
1- 35 3-0 *18 
1-8 3*0 *18 
27 3-0 78 
VOL. XXIT. 9/5/99 2 M 
