100 ON THE HEAT EVOLVED DURING 
615. Hence 2°648 is the resistance to electro- 
lysis of this solution. Of this, part is due to the 
separation of zinc from oxygen, and part, to the 
transfer of sulphuric acid from the oxide of zinc 
to the water. We must eliminate the latter,— 
and I know not a better way of doing so, than 
that of converting 2°82 (the heat evolved when 
oxide of zinc is dissolved in dilute sulphuric acid, ) 
into 0°46, (its equivalent of resistance to electro- 
lysis, ) and subtracting this from 2°648. Thus we 
obtain 2°188*, the intensity occupied in separating 
zinc from oxygen, and giving the latter the ga- 
seous state. 
But we have seen that the intensity of the union 
of non-gaseous oxygen with zinc is represented 
by 1°732. Therefore 2°188—1-732=0°456, the 
intensity due to the assumption by oxygen of the 
gaseous state. 
Again, the resistance to electrolysis of solution 
of sulphate of oxide of copper is 1-702: and 
* This number is rather over the truth, (p. 102,) but as I 
have found by a recent experiment, in which oxywater was 
substituted for the nitric acid of Grove, that the intensity of 
Grove’s arrangement (from what cause I cannot conceive) is 
probably greater than is represented by the union of non-ga- 
seous oxygen with zine, there is probably a compensating error. 
