112 
MESSRS. W. DE LA RUE AND H. W. MULLER ON THE 
0-0001713X6S-4 AAA1AO oo cm a 
— =0 0010833 grm. of silver per second, 
reduced by 1 cell with a resistance of 1 ohm. 
A similar experiment with acidulated water in a voltameter having a resistance of 
20 ohms gave in 6 minutes 7'2133 cub. centims. of mixed gases at 0° Cent, and 
760 millims ; this corresponds to 0‘001035 grm. of silver reduced per second by 1 cell 
through a resistance of 1 ohm, showing, on the supposition that the resistance had 
been accurately ascertained, that in the latter case about 5 per cent, of the current 
passed without an equivalent evolution of the mixed gases. 
In order to eliminate small errors in the determination of the internal resistance of 
the battery, a single cell was built up of 10 rod cells so as to form one element of 
small resistance, namely, 0 - 297 ohm; it was coupled up to the nitrate of silver 
decomposition cell through various resistances, making from 1'672 to 106 '175 ohms 
total resistance in the circuit, the deflection of the galvanometers remained constant 
for 30 hours. The mean of four experiments gave 0'0010945 grm. of silver deposited 
per second by 1 AgCl cell through 1 ohm. This amounted to 94 per cent, of 
Kohlrausch’s number multiplied by 1 '03 volt, the electro -motive force of the chloride 
of silver cell — ■ 
Q-Q11868*xl- p8 y 
10 
Kohlrausch’s number being for the C. G. S. electro-magnetic unit, of which the Weber 
is one-tenth. 
When the deposit of oxychloride has caused a greater reduction of current than is 
convenient, the battery may be restored to its original condition by scraping the zinc 
rods, which is easy of accomplishment ; thus, 2400 rod cells charged up December 
15th, 1875, after being short-circuited for about half-an-hour to start the battery, 
evolved in a voltameter 2 cub. centims. of mixed gases in a minute ; on April 9th, 
1877, the battery only evolved 0*45 cub. centims. per minute. Twenty cells were 
taken to pieces, and the zinc rods scraped to remove the crust which had formed on 
them, this battery of 20 then evolved 2 '8 5 cub. centims. per minute. The whole of the 
batteries were subsequently taken to pieces, and the zinc rods scraped ; it required, on 
the average, six days to take to pieces and re-make up each 1200 cells of the rod 
battery.f From each of the batteries, 6 and 7, each containing 1200 cells, there was 
* Everett’s C G. S. Units, p. 77. 
f This operation was conscientiously performed by a pupil and workman of Messrs. Tisley and Spieler, 
Mr. Henry Hawkins, who has put together most of our batteries, and of whose zeal and intelligence we 
are able to speak in high terms. 
Since this communication was sent in, it has been found that a more expeditious mode of restoring 
the battery to its original current force is to withdraw the small paraffin plug used to close the 
hole in the stopper through which the cells are charged, and to introduce into each cell, containing 
50 cub. centim., 1 cub. centim. of pure hydrochloric acid, sp. gr. 1T6, containing 318 per cent. HC1 gas, 
