596 
MESSRS. R. T. GLAZEBROOK AND S. SKINNER ON THE 
Table IV. 
1 
Date. 
<d 
-4-3 
Ou 
O- 
CD 
-+=> 
P* 
co 
GO 
Mercury. 
March 21. 
April 21. 
May 2. 
May 21. 
August 7. 
n— 1 
r—1 
-P 
CO 
b£> 
P 
November 14. 
1 
1 
December 15. 
Tempera¬ 
ture 
Zinc sul 
O 
r-l 
P 
O 
f-t 
<D 
1 
10 
13 
17 
15 
16-8 
17-8 
10-8 
16-5 
Number. 
25 
OC 
7 
6 
- 2 
1 
2 
1 
-1 
2 
2 
0 
26 
oc 
7 
0 
- 3 
4 
8 
5 
0 
4 
4 
2 
27 
oc 
s 
0 
1 
6 
7 
6 
0 
3 
2 
2 
28 
oc 
s 
0 
0 
5 
10 
3 
0 
4 
3 
6 
29 
oc 
€ 
0 
- 2 
- 1 
1 
3 
1 
2 
1 
-1 
N 0 crystals 
30 
oc 
€ 
0 
- 8 
1 
5 
0 
-2 
2 
2 
4 
added 
Much crystals 
31 
P 
r 
i 
-40 
-16 
-12 
4 
-1 
3 
6 
3 
added 
32 
p 
r 
L 
-51 
-28 
-19 
-25 
-1 
4 
6 
3 
33 
P 
r 
K 
- 3 
1 
3 
2 
1 
5 
4 
2 
34 
P 
V 
K 
- 9 
2 
3 
0 
-1 
4 
4 
0 
35 
P 
V 
K 
- 5 
- 8 
— 2 
- 6 
— 2 
3 
4 
2 
The results are of much interest. All the cells are now within about 1 in 1000 
of the standard ; for, as we have said, one of our units is '00025 volt; thus six of 
these units is *0015 volt, or rather over ] in 1000 . The first six cells have been, 
it will be seen, nearly right from the beginning; those with the good mercurous 
sulphate S were, two days after being set up, extremely ^ close to the standard, while 
25 and 26, 29 and 30, in which the bad sulphates, y and e, were used after treatment 
with the mercury, were rather too low. Nos. 31 and 32 were originally far too low 4 
this would appear to be due to impurity in the mercury, for the zinc and mercurous 
sulphates were good, while the mercury was only cleaned by filtering. Moreover 
No. 33, which only differs from No. 32 in having distilled mercury, is nearly right. 
The mercury used in Nos. 33, 34, 35 was distilled at atmospheric pressure, and the 
somewhat low results given by these cells may be due to this ; in the case of Nos. 34 
and 35 it would appear more likely that they have a similar source to the low 
numbers found in Nos. 25, 26, 27, and 30. The differences of E.M.F. had, however, 
been considerably reduced, except in the case of No. 32, some two months after 
making the cells, while at the next observation, after an interval of three months 
more, the differences had practically vanished. I 11 the first three comparisons the 
reference to the standard was somewhat indirect; the absolute values of the numbers 
given cannot be trusted to very high accuracy, and the temperature is a little 
uncertain. It appears as if the values of the E.M.F. of Nos. 31 and 32 are still 
rising. 
