There appears to be a luminous layer of minute
sparks under the foils, and there is a strong smell of ozone. In a
dielectric which heats, there may be three kinds of conduction, viz.,
metallic, when an ordinary conductor is embedded in an insulator;
disruptive, as probably occurs in the case of mica; and electrolytic,
which might occur in glass. In a transparent dielectric the conduction
must be either electrolytic or disruptive, otherwise light vibrations
would be damped. The dielectric loss in a cable may be serious.
Calculating from the waste in a condenser made of paper soaked in hot
ozokerite, the loss in one of the Deptford mains came out 7,000 watts.
Another effect observed at Deptford is a rise of pressure in the
mains. There is as yet no authoritative statement as to exactly what
happens, and it is generally assumed that the effect depends on the
relation of capacity to self-induction, and is a sort of resonator
action. This would need a large self-induction, and a small change of
speed would stop the effect. The following explanation is suggested.
When a condenser is put on a dynamo, the condenser current leads
relatively to the electromotive force, and therefore strengthens the
field magnets and increases the pressure.
[Illustration: T_{1} and T_{2} are large transformers; t_{1} and t_{2}
are small transformers or voltmeters V_{1} and V_{2}. The numbers 1,
4, 1, 25, represent their conversion ratios.
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