ELECTRO-CHEMICAL EQUIVALENT OF SILVER, 
451 
Thomson'" found a smaller number, viz., 1’00041, and with this our results were first 
reduced. Later, however, we found reason to suspect that the actual change was 
greater than this, and accordingly made some special observations to clear up the 
doubt. One cell (No. 6) was mounted in a large test tube, the gutta-percha-covered 
leading wires being brought through a tightly-fitting indiarubber cork, and was kept 
constantly at 0° centigrade by being surrounded with ice. With this No. 1 at the 
temperature of the room was compared from day to day, with the result that its 
temperature coefficient is about the double (1’00082) of that given by Weight and 
Thomson. A similar result was found by Helmholtz,! who remarks that the effect 
of temperature may vary according to the preparation of the cell. 
Using this number to reduce the result of March 29, we have to subtract ’0022, 
thus obtaining 
E=1’4539 B.A. volts 
as the electromotive of No. 1 Clark at 15°. 
Table XI. 
I. 
Date, 
1883 and 1884. 
11. 
Cell used. 
III. 
Temperature. 
IV. 
E.M.F. 
in B.A. volts. 
V. 
E.M.F. 
relative to 
No. 1. 
VI. 
E.M F. 
of No. 1. 
VII. 
Correction 
to 15°. 
VIII. 
E.M.F. 
in B.A. volts, 
corrected to 
15°. 
October 23 . 
Clare No. 1 
15° 9 
1-4542 
1-0000 
1-4542 
+ •0010 
1 4552 
November 20 
„ No. 2 
15-3 
1-4549 
1-0006 
1-4540 
+ -0004 
1-4544 
„ 21 . 
„ No. 1 
14-9 
1-4543 
1-0000 
1-4543 
-•0002 
1-4541 
„ 22 . 
„ No. 1 
14-9 
1-4533 
1-0000 
1-4533 
-•0002 
1-4531 
December 4 
„ No. 1 
15-8 
1-4524 
1-0000 
1-4524 
+ •0010 
1-4534 
„ 11 • 
„ No. 1 
17-2 
1-4524 
1-0000 
1-4524 
+ "0026 
1-4550 
„ 12 . 
„ No. 2 
15-8 
1-4549 
1-0008 
1-4537 
+ -ooio 
1-4547 
January 28 . 
„ No. 2 
15-0 
1-4541 
1-0000 
1-4541 
+ 0000 
1-4541 
March 20 . . . 
„ No. 4 
15-8 
1-4533 
•9998 
1-4536 
+ •0010 
1-4546 
„ 25. . . 
„ No. 1 
13’5 
1-4560 
1-0000 
1-4560 
—-0018 
1-4542 
„ 29. . . 
„ No. 4 
131 
1-4558 
•9998 
1-4561 
-•0022 
1-4539 
April 2 . . . 
„ No. 1 
] 6-1 
1-4524 
1-0000 
1-4524 
+ •0014 
1-4538 
„ 7 . . . 
„ No. 1 
15-5 
1-4535 
1-0000 
1-4535 
+ •0006 
1-4541 
Mean .... 
15’3 
14542 
§37. This determination and twelve others, made at intervals from Oct., 1883, to 
April, 1884, are exhibited in Table XI.J They are all deduced from observations with 
the current-weighing apparatus. It will be seen that there is little or no evidence of 
any progressive change. The casual fluctuations are of course partly due to errors of 
observation, but it would seem are principally to be attributed to real variations of 
* Phil. Mag., July, 1883, p. 36. 
f Sitzungsber. d. Kon. Akad. d. Wiss. zu Berlin, February, 1882, 
1 For continuation of Table XI. see notes. 
3 M 2 
