66 DR. FARADAY’S EXPERIMENTAL RESEARCHES IN ELECTRICITY. (SERIES XVI.) 
sumption also, for it is supported not by any independent measurement or facts (1808.), 
but only by the theory which it is itself intended to support. 
1811. Guided by this opinion, and with a view to ascertain what is, in an ac- 
tive circle, effected by contact and what by chemical action, I endeavoured to find 
some bodies in this latter class (1810.) which should be without chemical action on 
the metals employed, so as to exclude that cause of a current, and yet such good con- 
ductors of electricity as to show any currents due to the contact of these metals with 
each other or with the fluid : concluding that any electrolyte which would conduct 
the thermo current of a single pair of bismuth and antimony plates would serve the 
required purpose, I sought for such, and fortunately soon found them. 
i. Exciting electrolytes, 8$c., being conductors of thermo and- feeble currents. 
1812. Sulphur et of potassium. — This substance and its solution were prepared as 
follows. Equal weights of caustic potash (potassa fusa) and sulphur were mixed and 
heated gradually in a Florence flask, till the whole had fuzed and united, and the 
sulphur in excess began to sublime. It was then cooled and dissolved in water, so 
as to form a strong solution, which by standing became quite clear. 
1813. A portion of this solution was included in a circuit containing a galvano- 
meter and a pair of antimony and bismuth plates ; the connexion 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 cur- 
rent; but the moment the junction of the antimony and bismuth was either heated or 
cooled, the corresponding thermo current was produced, causing the galvanometer- 
needle to be permanently deflected, occasionally as much as 80°. Even the small 
difference 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 pla- 
tinum were used, the application of the spirit-lamp to the junction of these metals 
produced a thermo current which instantly travelled round the circuit. 
1814. Thus this electrolyte will, as to high conducting power, fully answer the 
condition required (1811.). 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. 
1815. 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. 
1816. A portion of this acid was mixed with nearly its volume of pure water; the 
