392 



Dr. R. A. Lehfeldt on Electromotive 



shown in fig. 3. The accumulator A was connected to the 

 terminals of the box a d : 1000 ohms taken out of the arm b c, 

 and about 430 from cd, making the E.M.F. between b and c 

 equal to that of a Clark cell. The Clark or other cell was 



Fig. 3. 



connected by a multiple switch from the tapping-key at e 

 through a Crompton " midget " galvanometer to c, the wire 

 touching on the way at the other tapping-key f; putting 

 down the latter short-circuits the galvanometer and damps 

 it, while the right-hand key puts the experimental cell in 

 circuit. The E.M.F. between a and d having first been 

 found when the Clark is in circuit, may be regarded as 

 known for the subsequent experiments ; for although the 

 total resistance between a and d varies, it is always so large 

 as to leave the E.M.F. between the terminals of the ac- 

 cumulator practically unaffected. 



The results obtained are shown in the following tables and 

 also on the accompanying diagram (p, 397) : — 



Zinc Chloride. 



1st Series. — Solution (x) prepared as described above. Den- 

 sity 1*1238 at 19°' 7 (referred to water at 4°) : corre- 

 sponding concentration calculated to be 2*19 times 

 normal. Amalgam cells. 



gm.-equiv. /litre 

 (1U00 C). 





E.M.F. 



E.M.F. 



E.M.F. 



logC=-i//. 



observed. 



differences. 



from normal. 





Volts. 



Volts X 10-4. 



Volts x 10- J. 



ar=2-19 



3-340 



10406 





+249 



xl'2 



3-039 





> 220 



4- 29 



a/4 



4-738 





> 225 



-196 



x/8 



4-437 





> 230 



-426 



x/W 



4~136 





> 228 



-654 



aV32 



5 835 





> 215 



-869 



i 



