COMPARATIVE PRODUCE OF DIFFERENT BATTERIES. 



67 



Constancy of Batteries. But the first hour of the action of most 

 batteries differs from any hour afterwards, so that one kind of 

 battery may be most useful for a short time, and another sort if the 

 action is to be continued for a length of time. The following table 

 will illustrate this remark, the condition being the same as in last 

 experiment, or the last experiments being continued, and the results 

 taken every hour for seven successive hours: 



To make this comparison more practical, larger plates were used 

 for the battery, and proportionately larger electrodes, and the 

 battery kept in operation until one pound of copper was deposited, 

 renewing the acid, and brushing the zincs every 24 hours. The 

 time taken to effect this was: 



Grove's Battery 19 i hours. 



Single ceU ...... 45 



Daniell's 1 49 



Smee's 147 



Wollaston's 151 



Comparative Produce of Batteries. The expense of the materials 

 used in these experiments was as follows (of course the materials 

 will differ in cost both at different times and in different localities, 

 and more common materials may be used): 



By the process with Grove's battery, one pound of deposited 

 copper cost , 



lib. Copper, from positive electrode ... 1 



l^lb. Amalgamated zinc 10 



l^lb. Nitric acid 09 



Sulphuric acid 01 



2 8 

 Add time, say halfpenny per hour, for comparison . 9| 



35} 



1 The Darnell's Battery used in this experiment had flat plates, not circular, as 

 described at page 36. 



