ELECTRO-CHEMICAL EQUIVALENT OF SILVER. 
4 39 
amount to nearly half a second on a total in some cases as low as 2700 seconds. 
When so many experiments are made we must expect the cases to arise in which the 
small errors, due to various causes, are accumulated in the result. 
§ 26. We may now calculate the results of our experiments in absolute measure. 
In the notation of § 15 we have, as the relation between the current i and the differ¬ 
ence of weighings observed in air to, 
where 
iz=jx x /m, 
^='037048. 
If w be the electro-chemical equivalent of silver in C.G.S. measure, viz., the 
quantity of silver in grams deposited per second by the unit C.G.S. current, then 
the rate of deposit by current i is w.i, or Now, by the table this rate of 
deposit is v /m./2414 , 45 ; so that 
w— 
_ 1 _ 
241445 x ‘037048 
0111794. 
In terms of practical units we have as the quantity of silver in grams deposited per 
ampere per hour 
I-11794X 10~ 3 X3600 = 4°O246. 
The number found by Kohlrausch in his recent experiments is 
w=-011183, 
while that found by Mascart is 
w=-01124, 
The agreement between Kohlrausch and ourselves is perhaps as good as could be 
expected, and would be diminished almost to nothing were we to take in our experi¬ 
ments the weights as found after chying at 160° C., viz., before the strong heating. 
The account hitherto published by Kohlrausch is only an abstract, and does not 
explain how the deposits were treated.! 
§ 27. Considering that the silver voltameter may now be used satisfactorily for 
the standardising of current-measuring instruments, we have made some experiments 
in order to ascertain the limits within which the method is applicable. With regard 
to the strength of the nitrate solution there is considerable latitude when the currents 
are weak, e.g., not exceeding ^ ampere. In such cases a 4 per cent, solution may 
be used satisfactorily in our voltameters. However, for practical purposes at the 
present time the object will usually be to measure stronger currents, and then it is 
advisable to keep the solution up to 15 or 30 per cent- If the solution is too weak in 
relation to the density of current, the deposit has a tendency to looseness, and is 
* ‘Journal de Physique,’ March, 1882. f See Notes. 
