A POTENTIOMETER FOR THE DE- 
TERMINATION OF HYDROGEN ION 
‘CONCENTRATION IN SOLUTIONS 
+ Si ceu = 
SS 
—> 
[HE POTENTIOMETER illustrated above is now being used by a number of 
investigators for measuring the E. M. F. between the Hydrogen and Calomel 
electrodes in Hydrogen Ion Concentration determinations. It is rapidly replacing 
the electrometer for such work for the following reasons: first, it is much more sensi- 
tive than the electrometer; second, its use does not entail the annoying delays 
met with in the use of the electrometer when overcharged and thus polarized. 
The Leeds and Northrup Potentiometer has two ranges. Normally measure- 
ments may be made up to 1.6 volts by steps of .00001 volt. A range changing 
plug enables measurements to be made up to .16 volt by steps of .000001 volt. 
The precision of adjustment is such that on the high range measurements from 
1 volt up may be made to a precision of better than 1/50%. On the low range 
measurements from .01 volt up may be made to the same degree of precision. 
The instrument and its accessories require little or no attention. Its manipu- 
lation is simple. | 
A full description of this potentiometer will be sent upon request, as well as a 
list of some of those who are now using it for Hydrogen Ion Concentration 
determinations. 
THE LEEDS & NORTHRUP CO. 
ELECTRICAL MEASURING INSTRUMENTS 
4930 STENTON AVENUE PHILADELPHIA 
