92 ON THE HEAT EVOLVED DURING 
The heat evolved by wire, having been ascer- 
tained by these three experiments, furnished the 
means of calculating the subsequent numbers of 
column 8, according to the well-established law 
of resistance to conduction and square of current. 
The t2me during which the electrolysis was 
allowed to proceed, varied from 73’ to 10’. The 
results of the table are however, for the sake of 
uniformity, invariably reduced to ten minutes of 
time. The quantities of heat are reduced to the 
capacity of a pound avoirdupois of water, by 
making the requisite corrections (deduced from 
careful experiments) for sp. heat, and the influ- 
ence of the atmosphere. The cwrrent is, as in 
my former papers, expressed in degrees. (1°, 
passing uniformly during an hour, decomposes a 
chemical equivalent expressed in grains: as 9 grs, 
of water, 41 grs. of oxide of zinc, &c.) 
By inspecting the Table, it will be observed 
that the heat actually evolved is in every case of 
electrolysis greater than that which is due to the 
product of the resistance to conduction and the 
square of the current. In a former paper* I 
ascribed this to the solution of oxygen at the 
* Phil. Mag. 1841, Vol. XIX, p. 274, (63.) 
