42 Messrs. Wright and Thompson on the Determination of 
From these figures the following are obtained by interpola- 
tion : — 
Current. 
Potential-difference. 
4- Zinc. 
4- Copper. 
*2-«l- 
•000005 
•00001 
•00002 
•00004 
■021 
•045 
•085 
•168 
1-075 
1-101 
1-147 
1-232 
1-054 
1-056 
1-062 
1-064 
Precisely similar results were obtained in numerous other 
analogous experiments. Thus the following Table illustrates 
some of the figures obtained, the + zinc plate originally 
employed being replaced by a plate of the same size, I. of 
bright copper, II. of electro-copper, III. of amalgamated 
copper, IV. of bright cadmium, V. of bright silver. 
C.G.S. 
current. 
Values of e, 2 — e x obtained. 
I. 
II. 
III. 
IV. 
V. 
•000005 
•00001 
•00002 
•00004 
1-063 
1-067 
1-073 
1-075 
1-054 
1-057 
1-061 
1-068 
1-065 
1076 
1-084 
1-099 
•315 
•324 
1-486 
1-498 
1-503 
1-512 
143. A still better illustration of the regular rise in value 
of e 2 —e 1 with the current is afforded by the following series of 
numbers obtained as the average results of several sets of 
observations very carefully made — A with a bright zinc -f 
electrode, B with one of bright cadmium, C with one of 
bright copper, and D with one of bright silver. In every case 
the mean temperature was the same within two or three tenths 
of a degree (varying from 17°*55 to 17°*9 throughout). In 
the last case it was found that, whilst perfectly steady readings 
could be obtained with current-strengths up to something like 
*0007, with higher strengths this was no longer the case, silver 
peroxide being apparently formed instead of silver sulphate. 
In these experiments all the plates exposed an area of 1*5 
square centim., the solution electrolyzed being a nearly satu- 
rated one of pure zinc sulphate, renewed for each series ; the 
plates were about 5 centim. apart, the tube holding them being 
3 centim. in internal diameter. 
