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LXXXIII. On the Thermo-electric Currents developed be- 

 tween Metals and Fused Salts, By Thomas Andrews, 

 M.D., Professor of Chemistry in the Royal Belfast Institur- 

 tion. * 



T^HE interesting discovery made by Faraday of the high 

 -■" conducting power of certain fused salts for voltaic electri- 

 city, led me to expect that electrical currents might be pro- 

 duced by bringing them into contact with the metals, analo- 

 gous to the thermo-electric currents observed by Seebeck. 

 Having easily succeeded in verifying this conjecture, and 

 having observed that the currents thus produced exhibited 

 some remarkable properties, I submitted them to a careful 

 examination, the result of which forms the subject of the pre- 

 sent paper. 



To detect the presence of the electrical current, a very de- 

 licate galvanometer, constructed for me by M. Gourjon of 

 Paris, was employed, in which the copper wire made nearly 

 3000 revolutions round the lower needle, and the system of 

 needles was rendered as perfectly astatic as possible. A gal- 

 vanometer having 20 or 30 coils, with astatic needles, will be 

 found, however, sufficiently sensible to give decided indications 

 of the passage of the principal currents which I shall have oc- 

 casion to describe. 



Having taken two similar wires of platina (such as are used 

 in experiments with the blowpipe), and connected them with 

 theextremities of the copper wire of the galvanometer that has 

 just been described, I fused a small globule of borax in the 

 flame of a spirit-lamp, on the free extremity of one of the 

 platina wires, and introducing the free extremity of the other 

 wire into the flame, I brought the latter, raised to a higher 

 temperature than the former, into contact with the fused glo- 

 bule ; the needle of the instrument was instantly driven with 

 great violence to the limit of the scale. The direction of the 

 current, as indicated by the deflection of the needle, was from 

 the hotter platina wire through the fused salt to the colder 

 wire. A permanent electrical current in the same direction 

 was obtained, by simply fusing the globule between the two 

 wires, and applying the flame of the lamp in such a manner 

 that, at the points of contact with the fused salt, the wires 

 were at different temperatures. 



To discover whether the current had sufficient intensity to 

 pass through acidulated water, a column of water (to which 

 a few drops of sulphuric acid had been added), whose length 

 was about half an inch, was interposed in the course of the 



• Communicated by the Author. 

 Third Series, Vol. 10. No. 63. June 1837. 3 K 



