Electrolytes Good Conductors 239

plates; the connection with the electrolyte was made by two
platinum plates, each about two inches long and half an inch
wide: nearly the whole of each was immersed, and they were
about half an inch apart. When the circuit was completed,
and all at the same temperature, there was no current; but the
moment the junction of the antimony and bismuth was either
heated or cooled, the corresponding thermo current was pro
duced, causing the galvanometer-needle to be permanently
deflected, occasionally as much as 80°. Even the small dif-
ference of temperature occasioned by touching the Seebeck
element with the finger, produced a very sensible current
through the electrolyte. When in place of the antimony-
bismuth combination mere wires of copper and platinum, or iron
and platinum were used, the application of the spirit-lamp to
the junction of these metals produced a thermo current which
instantly travelled round the circuit.

802. Thus this electrolyte will, as to high conducting power,
fully answer the condition required (799). It is so excellent in
this respect, that I was able to send the thermo current of a
single Seebeck's element across five successive portions con-
nected with each other by platinum plates.

803. Nitrous acid.—Yellow anhydrous nitrous acid, made
by distilling dry nitrate of lead, being put into a glass tube and
included in a circuit with the antimony-bismuth arrangement
and the galvanometer, gave no indication of the passage of the
thermo current, though the immersed electrodes consisted each
of about four inches in length of moderately thick platinum
wire, and were not above a quarter of an inch apart.

804. A portion of this acid was mixed with nearly its volume
of pure water; the resulting action caused depression of tem-
perature, the evolution of some nitrous gas, the formation of
some nitric acid, and a dark green fluid was produced. This
was now such an excellent conductor of electricity that almost
the feeblest current could pass it. That produced by Seebeck's
circle was sensible when only one-eighth of an inch in length
of the platinum wires dipped in the acid. When a couple of
Inches of each electrode was in the fluid, the conduction was
so good that it made very little difference at the galvanometer
whether the platinum wires touched each other in the fluid or
were a quarter of an inch apart.1

1 De la Rive has pointed out the facility with which an electric current
passes between platinum and nitrous acid.—Annales de Chimie, 1828,
acxxvii. 278.. 217. 3 Ibid. p. 217. 4 Ibid. p. 225.32-237.a, 1837, xxi. p. 205.