ELECTRO-CHEMICAL EQUIVALENT OF SILVER. 457 
Fig. 5, § 29. H -pattern of Clark cell. 
A. Platinum wires sealed through glass. 
B. Amalgam of zinc. 
C. Pure mercury. 
D. Mercurous sulphate. 
E. Saturated solution of zinc-sulphate. 
F. Corks. 
Notes. 
(Added December, 1884.) 
Note to $ 25. 
In order to investigate the effect (if any) of temperature upon the amount of silver 
deposits, we have made experiments in which voltameters maintained at different 
temperatures were exposed to the same, current. The results, exhibited in the 
accompanying table, show a small but apparently real increase in the weight of 
the deposit as the temperature rises. Had the effect been in the other direction, we 
should have been disposed to attribute it to imperfections of manipulation, for the 
deposits from the warm solutions were always coarser and looser in texture than the 
corresponding deposits (upon the same area) from the cold solutions. 
1884. 
After usual washing and drying at 160°. 
After beating to verge of redness. 
Excess of hot 
over cold. 
Hot bowl 
(about 5(F). 
Bowl at 
temperature 
of room 
(15°). 
Cold bowl 
(4°). 
Hot bowl. 
Bowl at 
temperature 
of room. 
Cold bowl. 
May 27 . ' . 
2-3915 
2-3905 
'0010 
June 4. 
2-0230 
. , 
2-0220 
2-0229 
2-0221 
•0008 
July 22. . 
1-9050 
1-9013 
1-9049 
1-9043 
•0006 
July 31. . . 
1-9438 
1-9432 
1-9430 
1-9440 
1-9432 
1-9431 
•0009 
The solution was a 15 per cent, solution of pure nitrate of silver, and the anodes 
were of pure metal. The current was about ampere, and passed for rather more 
than an hour. 
The results here disclosed diminish, of course, the chemical significance of the 
number given as representing the electro-chemical equivalent of silver, but the 
variation is so small at ordinary laboratory temperatures that the use of the silver 
voltameter as a means of defining electric quantity is not practically interfered with. 
mdccclxxxiv. 3 n 
