ELECTROLYTES, BEING EXCELLENT CONDUCTORS. 
67 
resulting action caused depression of temperature, 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 dif- 
ference at the galvanometer whether the platinum wires touched each other in the 
fluid, or were a quarter of an inch apart*. 
1817- Nitric acid . — Some pure nitric acid was boiled to drive off all the nitrous acid, 
and then cooled. Being included in the circuit by platinum plates (1813.), it was 
found to conduct so badly that the effect of the antimony-bismuth pair, when the dif- 
ference of temperature was at the greatest, was scarcely perceptible at the galvano- 
meter. 
1818. On using a pale yellow acid, otherwise pure, it was found to possess rather 
more conducting power than the former. On employing a red nitric acid, it was 
found to conduct the thermo-current very well. On adding some of the green ni- 
trous acid (1816.) to the colourless nitric acid, the mixture acquired high conducting- 
powers. Hence it is evident that nitric acid is not a good conductor when pure, but 
that the presence of nitrous acid in it (conjointly probably with water), gives it this 
power in a very high degree amongst electrolytes^. A very red strong nitric acid, 
and a weak green acid, (consisting of one vol. strong nitric acid and two vols. of water, 
which had been rendered green by the action of the negative platinum electrode of a 
voltaic battery.) were both such excellent conductors that the thermo current could 
pass across five separate portions of them connected by platinum plates, with'so little 
retardation that I believe twenty interruptions would not have stopped this feeble 
current. 
1819. Sulphuric acid . — Strong oil of vitriol, when between platinum electrodes 
(1813.), conducted the antimony-bismuth thermo current sensibly, but feebly. A 
mixture of two volumes acid and one volume water conducted much better, but not 
nearly so well as the two former electrolytes (1814. 1816.). A mixture of one volume 
of oil of vitriol and two volumes saturated solution of sulphate of copper conducted 
this feeble current very fairly. 
Potassa . — A strong solution of caustic potassa, between platinum plates, conducted 
the thermo current sensibly, but very feebly. 
1820. I will take the liberty of describing here, as the most convenient place, other 
* De la Rive has pointed out the facility with which an electric current passes between platinum and nitrous 
acid. Annales de Chimie, 1828, xxxvii. 278. 
t Schcenbein’s experiments on a compound of nitric and nitrous acids will probably bear upon and illustrate 
this subject. Bibliotheque Universelle, 1817, x. 406. 
