CAPACITY AND RESIDUAL CHARUE OF DIELECTRICS. 
115 
two electrodes, polarization of electrodes is avoided, and the gradually-diminishing 
current through the galvanometer is that due to residual charge. The conductivity 
of the jar is determined by removing the glass distance-piece g, connecting 7 to 9, 
8 to 12, and 10 to 11, and noting the steady deflection on the galvanometer for a 
given charging potential difference. 
In the ice experiment, the conductors from 3, 4, are used both for charging and 
discharging. The form of condenser used when dealing with ice and liquid dielectrics 
is shown in fig. 2. It consists of seven platinum plates, a, h, c, d, e, f, g, each measuring 
2 inches by 3 inches, and of a thickness '2 millim., separated from each other by a distance 
flp Z. 
of 2‘7 miilims. To each plate are gold-soldered four platinum wires—two top and two 
bottom. Plates a, c, e, g, form the outer coating of the condenser, and are kept in 
their relative positions by cross connecting wires h, gold-soldered to the wires at each 
end of each plate. Similarly, plates 5, d,f, which form the other and inner coating 
of the condenser, are fixed relatively to one another by cross connecting wires i. The 
relative jDositions of the two sets of plates are fixed by glass rods 1, 2. The terminals 
of the condenser are, for the inner j^lates the prolonged wire 3, and for the outer 
plates the wires 4, 4. These are bent round glass rods 5, G, which resting on the top 
of a beaker support the plates in the fluid. The glass tubes on the wires 3, 4, 4, are 
for the purpose of securing good surface insulation. The glass beaker is conical, so as 
to remain unbroken when freezing the distilled water within. Tliis was accomplished 
Q 2 
