in which V and V' are potentials of the two points; d' and d the two
distances between the discs necessary for equilibrium; S the area of the
disc and F the force of attraction in dynes. (See Idiostatic Method.)
High Bars of Commutator.
Commutator bars, which in the natural wear of the commutator, project
beyond the others. The surface then requires turning down, as it should
be quite cylindrical.
High Frequency.
A term used as a noun or as an adjective to indicate in an alternating
current, the production of a very great number of alternations per unit
of time--usually expressed as alternations per second.
Hissing.
A term applied to a noise sometimes produced by a voltaic arc; probably
due to the same cause as frying, q. v.
Hittorf's Solution.
A solution used as a resistance. It is a solution of cadmium iodide in
amylic alcohol. Ten per cent. of the salt is used. It is contained in a
tube with metallic cadmium electrodes. (See Resistance, Hittorf' s.)
Fig. 196. HITTORF'S RESISTANCE TUBE.