towards the Theory of Thermo- electricity, 209 



sistent, and indicated that the thermo-electric current did 

 consume caloric in its production. 



4. If this inference were true, it should follow that the wires 

 heated to the same degree, should cool much more rapidly 

 when kept in contact the whole time of cooling, than when 

 kept all the time separate. They were therefore heated as 

 before, and being thrust in, the fluid was allowed after rising 

 to recede to 70°; from which its time of descent to 20°, i. e. 

 50°*, was observed by a seconds watch, — the wires remaining 

 in contact. 



The same proceeding was repeated, the wires remaining 

 separate. 



Precision, for reasons above given (3.), was unattainable; 

 and the conclusion was only to be drawn from the average of 

 many experiments. This average gave 60 s for the closed 

 wires, and less than 60 s for the separated ones ; thus the 

 cooling seemed retarded, rather than accelerated, by the con- 

 tact, and consequent electrical current. All that repetition 

 and examination could do to avoid discrepancy was attended 

 to, and yet these experiments seemed to contradict the pre- 

 ceding ones. 



5. The mode of interrogation was reversed. If caloric dis- 

 appeared in the production of thermo-electricity, it was not 

 unlikely that where caloric became latent, thermo-electricity 

 might appear. 



A glass siphon being suspended by the ends over a spirit 

 lamp, tin was dropped in and melted there, until the siphon 

 was nearly full ; the ends were then connected with the poles 

 of the magnetest by long and similar copper wires, tinned at 

 the points. Although copper is (generally) positive to tin, no 

 current ensued, because both ends were alike in contact with 

 copper. A hot iron wire being now plunged into the tin, at 

 one end of the siphon, gave a deflection of 6°; and when 

 transferred to the other end, a deviation to thesame amount, 

 in the contrary direction ; and so repeatedly (37.) : thus 

 manifesting a current when electricity was developed. A 

 slip of tin was now plunged into one end : of course no 

 deviation could be expected (37.). This tin was allowed to 

 melt there, by which caloric must have become latent. The 

 fusion was gradual, and in full contact with metal on all sides; 

 the electricity, if any were produced, must therefore have been 

 continuous, and could not have acquired tension. It would 



* Not degrees of Fahrenheit, or of any other standard scale ; for the heat 

 of the air about the wires must have been very different from that about 

 the glass. 



Third Scries. Vol. 3. No. 15. Sept. 1833. 2 E 



