270 W. Hallock—Smee Battery and Galvanic Polarization. 
resistance column was determined from time to time in the 
Wheatestone’s bridge in the ratio 1,000 to 10,000. The resist- 
ance can of course be easily varied by varying the dimensions 
of the capillary tube or the amount of water and salt dissolved 
in the alcohol. 
Objection might be made to the use of the galvanometer for such 
galvanometer, but a simple calculation will show that it would 
require a polarization equal to one and a half Daniell’s to con 
sume 0'1™" of hydrogen per minute working in a circuit 
whose resistance was 150,000 S. KE. That this quantity of gas 
may be neglected at first when the electrodes are still heavily 
coated is evident. This theoretical refutation of the ahove ob- 
jection was strengthened by the following experiment. Two 
platinum plates were twice equally strongly polarized, and the 
first time connected through 150,000 8, EB. and left and the 
curve of the diminution of the polarization plotted; the secon 
time the similar circuit was only closed once a minute and only 
for from 6 to 8 sec. and then opened again, and the curve 
plotted in this case. The two curves showed that the con 
sumption of gas by the current when left closed did not make 
itself apparent until after 17 min., i. e. it may be neglected for 
the first five minutes at least. 
The electromoter possesses the advantage, that with the pro 
per use of a switch or commutator it can be charged to a potel 
sarily has a long time of vibration and is weakly damped: # 
very convenient form of the switch is that made by Hartman 
in Wiirzburg, being a slight improvement upon the Weber. 
8. ON THE RIsE oF THE ELECTROMOTIVE FoRCE OF THE SMBP 
BATT 
_Exner* endeavors to explain those values of the electrom 
tive force of the Smee which fall above that calculated, from 
the thermal equivalents of its chemical reactions, E=0°75 D, 
the ground that the acid contains oxygen in solution which 
oxidizes the hydrogen evolved, and thus increases the thermal 
equivalent of the battery. a 
is question could be easily answered if it were possible t 
get and keep a cell entirely free from dissolved gases. Exner 
used the method of short circuiting the cell for a en time, bub 
* F, Exner, Wien. Ber., xxx, 1879 und Wied. Ann., x, p. 265, 1880: 
f 
