-, its tension, 268, 275.
----, evolution of heat by, 276.
----, its magnetic force, 277.
----, its chemical force, 278.
----, its spark, 280.
----, its physiological effects, 279.
----, its general characters considered, 268.
_Voltaic pile_ distinguished, 856, _note_.
----, electricity of, 875.
----, depends on chemical action, 872.
----, relation of acid and bases in the, 927.
----. _See_ Battery, voltaic.
_Voltaic spark_ without contact, 915, 956.
----, precautions, 958, 1074.
Voltaic trough, 989. _See_ Battery, voltaic.

_Water_, flowing, electric currents in, 190.
----, retardation of current by, 1159.
----, _its direct conducting power_, 1017, 1159, 1355.
----, ---- constant, 984.
----, electro-chemical decomposition against, 494, 532.
----, poles of, 494, 533, 558.
----, its influence in electro-chemical decomposition, 472.
---- is the great electrolyte, 924.
----, _the exciting electrolyte when_ pure, 944.
----, ---- acidulated, 880, 926, 1137.
----, ---- alkalized, 931, 934, 941.
----, electrolytic intensity for, 968, 981, 1017.
---- electrolyzed in a single circuit, 862.
----, its electrolysis definite, 732, 785, 807.
----, decomposition of by fine wires, 327.
----, quantity of electricity in its elements, 853, 861.
----, determined to either pole, 553.
_Wheatstone's_ analysis of the electric brush, 1427.
---- measurement of conductive velocity in metals, 1328.
_Wire, ignition of, by the electric current_, 853, _note_, 1631.
---- is uniform throughout, 1630.
_Wire_ a regulator of the electric current, 853, _note_.
----, velocity of conduction in, varied, 1333.
----, single, a current induced in, 170.
----, long, inductive effects in, 1064, 1118.
_Wollaston on_ decomposition by common electricity, 309.
---- decomposition of water by points, 327.

_Zinc, amalgamated_, its condition, 863, 1000.
----, used in pile, 999.
_Zinc_, how amalgamated, 863.
----, of troughs, its purity, 1144.
----, its relation to the electrolyte, 949.
----, its oxidation is the source of power in the pile, 919.
---- _plates of troughs_, foul, 1145.
---- ----, new and old, 1146.
----, waste of, in voltaic batteries, 997.

THE END.

PRINTED BY RICHARD AND JOHN E. TAYLOR.
RED LION COURT, FLEET STREET.

WORKS PUBLISHED BY RICHARD AND JOHN E. TAYLOR, _PRINTERS AND PUBLISHERS TO
THE UNIVERSITY OF LONDON_, RED LION COURT, FLEET STREET.

Daubeny on Active and Extinct Volcanos, Earthquakes, and Thermal Springs