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 1 
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 :— 
oe ee ees 
Muriaticacid, .. , 65°9 63:1 0°958 
Sulphuric acid, . . . 69°2 66°9 0967 
Nitrogen, «4: '.\j:03))» 602 67'3 67° 0-995 
Carbonic oxide, . . . 68'1 68°3 1:003 
Cyanogen,. . .. . 66°3 67° 1:610 
Carbonicacid, . . . 66°6 67°5 1-013 
Deutoxide of nitrogen, 66°2 67°3 1-016 
Protoxide of nitrogen, . 68°3 69°6 1-019 
0 as 68°3 69°6 1:019 
Olefiantgas, . .. . 68°2 76°2 Ne iw | 
Wmmonia,. 6 1/078 67°4 75'3 1118 
Hydrogen, .... 67°0 92°6 1°382 
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 
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