467 



tus, in order to sweep away, as completely as possible, the 

 atmospheric air ; the current was then arrested, and, the 

 connexions with the battery being established, the appear- 

 ance presented by the heated wire was noted, and the inten-" 

 sity of the current transmitted through it ascertained by]co \ 

 lecting the hydrogen evolved in the small cell during the 

 space of two minutes. The gas was next displaced by a 

 current of dry air, and the same experiment repeated. 

 During these experiments the battery was always in a very 

 constant state of action. The results are contained, in the 

 following table, in which the second column gives the quan- 

 tity of hydrogen extricated at each experiment with the 

 wire in air ; the third with the wire in the gas ; and the fourth 

 column expresses the ratios of these numbers — those in the 

 second being taken as unit : — 



As, however, the law, which connects the intensity of a 

 voltaic current traversing a wire with the temperature to 

 which it raises the wire, is unknown, these numbers do not 

 furnish us with the means of determining the exact variations 

 of temperature, sustained by the wire which was employed 

 in these experiments. But, as a term of comparison, it 



2r 



