90 ON THE HEAT EVOLVED DURING 
By ascertaining immediately before and after 
each experiment, the current which could pass 
when the battery and connecting wires (including 
that of the galvanometer) were only in the circuit, 
and that which could pass when an unit was added 
to this resistance by means of the standard of re- 
sistance ; we have, on the principles of Ohm, the 
equation av=b (v+1), or v= — , where a and 6 
are the above currents, and x is the resistance of 
the battery and connecting wires. 
This being known, we have the means of as- 
certaining the resistance to conduction of the 
electrolytic cell. It is obtained from the equation 
ce (a+y)=ar+, or y=(() —c)—, where 
(the other letters remaining as before) ¢ is the 
current observed during electrolysis, d is the 
number of cells in the battery, and z is the resist- 
ance to electrolysis of the electrolytic apparatus, 
calling (as I intend to do throughout this paper) 
the intensity of Daniell’s cell, unity. 
This resistance to electrolysis is obtained by 
observing the currents which pass through the 
electrolytic cell when different numbers of the 
battery cells are employed in propelling them. 
For this purpose the lowest two numbers adequate 
