374 H. 8. Carhart—Electromotive Force of a Daniell Cell. 
ArT. XLV.—Relation between the Hlectromotive Force of a 
Daniell Cell and the Strength of the Zine Sulphate Solution ; 
by H..S. CarHart. 
THE investigation here described was carried out in the 
physical laboratory of the University of Berlin in the spring 
of 1882, and was undertaken with a view to ascertain whether 
the variation in the strength of the zine sulphate solution sur- 
rounding the zine plate of a Daniell cell affected the electro- . 
motive force, and to what extent. 
It is well known that different experimenters have found 
different values of the electromotive force of a Daniell element. 
results may be partly due to difference of method; but it is 
easy to ascertain that slight changes in the condition of the 
plates or in the concentration of the solutions modify the value 
of the electromotive force to an appreciable extent. The 
method employed in this investigation was essentially the com- 
pensation method of Poggendorff.+ The two poles of the bat- 
tery A, the electromotive force of which is required, are 
S 8] 
| {1} 
* Everett’s Units and Physical Constants, p. 146. 
+ Wiedemann’s Elektricitat, p. 633. 
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