Battery, Grenet.
A plunge battery with zinc positive and carbon negative electrodes.
Electropoion or other chromic acid or bichromate solution is used as
depolarizer and excitant. The zinc plate alone is plunged into and
withdrawn from the solution.
Fig. 44. GRENET'S BATTERY.
Fig. 45. GROVE'S BATTERY.
Battery, Grove's.
A two fluid galvanic battery. A porous cup has within it a riband of
platinum, which is the negative plate; amalgamated zinc in the outer jar
is the positive plate. Dilute sulphuric acid (10 per cent. solution) is
placed in the outer jar, and strong nitric acid (40° B.) as a
depolarizer in the porous cups. Its E. M. F. is 1.96 volts.
It is objectionable, as it gives off corrosive nitrous fumes. These are
produced by the oxidation of the nascent hydrogen by the nitric acid, by
the following reaction:
3 H + H N O3 = 2 H2 O + N O. There are other reactions, one of which
results in the formation of ammonia by the reduction of the nitric acid
radical by the hydrogen. Ammonium can be detected in the spent liquids.