MORSE AND SARGENT. — RESISTANCE OF LEAD ACCUMULATOR. 597 



pected. The supposition of an inductance in the cell would explain 

 this change in the bridge reading, but a change in the frequency did 

 not affect a, while it did affect a'. 



The explanation would seem to be as follows: The configuration of 

 R suggests inductance, and an approximate calculation shows 'iirnLi 

 to be about 0.01. Now the value of I/'ItvuC^ is about 5. A change of 

 0.5 mm. from a to a corresponds to a change of 0.01 in l/^TrnCz. 

 Calculation gives about 0.01 for ^tttiL for the leads from the cell-switch 

 to the cell, corresponding to ^-miLi for the C^ arm of the bridge. From 

 these considerations it would appear that a rather than a' is more 

 nearly the point where C-^/C = a/b, for, with "cell in," the inductive 

 reactance of the C2 arm is balanced by that of the cell leads. 



Since Ci and C^ are about the same, and since Co, has an inductance 

 with it, while C\ has not, the reactance of the C2 arm will increase with 

 decrease of frequency faster than the reactance of the Ci arm ; in short, 

 the reactance of the Ci arm will become greater than that of the Ci 

 arm, and a' will diminish with decrease in frequency. On the other 

 hand, with " cell in," the two reactances will change equally with 

 change in frequency, that is, a will not change. 



7. From the average of all our measurements we have compiled the 

 values for the open circuit resistance of our cell at various tempera- 

 tures. They are as follows: 



TABLE I. 

 Open Circuit Resistance of Plante Plates at Various Temperatures. 



These values are plotted in the full-line curve of Figure 4. In the 

 dotted-line curve on the same figure are given the values for sulphuric 

 acid of the same concentration as that used in our cell. We have 

 chosen the two points indicated by larger circles as the points from 

 which to calculate the remainder of the curve, which is plotted from 

 the empirical formula 



Kt = Z; (1 + c# -f cH'') 



It will be seen that the cell resistance and the acid resistance fall 

 very closely together from zero to SO"". Above this point the cell re- 



