: 
; 
; 
W. Hallock—Smee Battery and Galvanic Polarization. 269 
in from 4 to 6 sec., even after a large deflection. It was so 
delicate that a single Daniell cell gave a deflection of 170 
scale-divisions with the scale 2™ from the mirror and 830,000 
. HK. in the circuit. 
Inasmuch as resistance coils of the necessary length of wire 
were constructed and calculated to see that they can lay no 
claim whatever to accuracy. 
The resistance used in this research was that offered by a 
column of a solution of Zn in hol, 1™™ in diameter 
in section and 200™™ long; this capillary tube was horizon- 
t i i n 
a 
diameter and 100™ high, in which stood the amalgamated 
zinc terminals. A better form however is to simply invert a 
case of the same salts dissolved in water. are was taken to 
prove that the polarization of the terminals could be ictijeet 
{5 Bunsen cells through 40 S. When afterward this resist- 
ance was compared with a wire coil of 200,000 S. KE. there 
could no difference detected in the results obtained. It 
moreover remained during the three months of its use constant 
to within the limits of an error caused by an error of 071° C, in 
the determination of its temperature. Of course the great ob- 
jection to liquid resistances is their large heat coefficient (from 
‘dD to 3°5 per cent for 1:0° C.). However there seems no reason 
why such resistances should not be used, where they can stand 
still in a case or water-bath and where about 0°2 to 05 per cent 
is sufficiently accurate. In all cases it is better to determine 
the resistance experimentally than to calculate it; the above 
* W. Hittorf, Wied. Ann., vii, p. 563, 1879. 
+ F. Exner, Wien. Ber., Ixxxiv, p. 528-529, 1881. 
t F. Kohlrausch, Pogg. Ann. Frgbd., viii, p. 1, 1877. 
