ELECTRIC DISCHARGE WITH THE CHLORIDE OE . SILVER BATTERY. 
99 
4th. Plate condensers : — 
D. Four condensers, formed of sheets of tinfoil and sheets of ebonite -g^-nd of 
an inch (O' 08 centim.) thick ; these each are in four sections : — 
Square feet. 
Square decim. 
Microfarad. 
D 1 
29 
269-5 
0-0924 1 
These support a charge 
D 2 
145 
1347 
0-4518 | 
i of 3600 cells, but are 
D 3 
145 
1347 
0-4704 | 
f liable to break down 
D 4 
145 
1347 
0-4741 J 
with 4800. 
E. Composed of tinfoil, separated by two sheets of vulcanized rubber, each 
•^-nd of an inch thick ; it is in four sections and has a total surface of 
75 square feet (698 square decim.), and a capacity of 0 - 1485 m.f. ; this 
bears a charge of 8040 cells. 
F. A condenser, composed of tinfoil and paraffined paper, in eight sections ; 
it has a total capacity of 4 2 ’8* m.f., and was made for us by Messrs. 
Varley ; it is capable of withstanding a charge with 3240 cells. 
G. A similar condenser, made under the direction of Dr. Muirhead, of 240 
sheets of tinfoil, with seven sheets of paraffined paper interposed ; this 
presents a surface of 364‘5 square feet (3386 square decims.), and has a 
capacity of 3 ‘9 4 microfarads ; it bears a charge of 8040 cells. 
H. Another, made under the direction of Dr. Muirhead, with eight sheets of 
paraffined paper between the layers of tinfoil ; the surface of this is 
2200 square feet (204'38 metres), and the capacity 20 microfarads. 
5th. We sometimes employ Leyden jars of the following dimensions : — 
Square inches. 
Square decim. 
Microfarad. 
H 1 
57 
3-68 
0-0016 
H 2 
258 
16-64 
0-0049 
H 3 
442 
28-51 
0-0066 
We give the foregoing particulars as affording useful information to other experi- 
menters who may have occasion to employ accumulators. The coil condensers we 
have found useful in certain cases, as for example those already communicated to the 
Royal Society.! The Varley condenser is of very great value for experiments with 
vacuum tubes, for when once charged up, and then disconnected from the battery, and 
the charge allowed to run down through a tube, it maintains a current frequently 
for ten minutes without replenishing, the phenomena varying as the potential 
falls ; when any particular phase in the stratification occurs, it may be sustained 
by connecting the condenser with the battery through a suitably-adjusted resist- 
ance, which permits of the inflow being exactly equal to the outflow. The potential 
at each end of the tube and at different points in the circuit may be ascertained for 
* The condenser of 47 - 5 m.f., described Proc. Roy. Soc., vol. xxiii. p. 358, broke down with 1080 cells, 
f Proc. Roy. Soc., vol. xxiii. p. 356. 
O 2 
