22 



PHYSICAL CHEMISTRY 



Obach's Wheatstone Bridge Table of B/D Where B = Meter Slide 

 from o to Sliding Contact and D = Remainder of Slide Wire. 



ductance may be made by bifilar winding or lateral compression 

 of the coil into one plane. A sharp tone minimum may be ob- 

 tained and the telephone not be sensitive enough to detect it. A 

 telephone that is tuned to the pitch of the induction coil is better, 

 but the tune of the coil may change even though the spring of 

 the vibrator is very stiff. A high frequency generator or Vree- 

 land oscillator should not change in pitch, and is necessary for 

 the greatest accuracy. 



Since 1 ° rise in temperature causes an increase in electric con- 

 ductivity of about 2.5 per cent, the conductivity cell must be 

 placed in a water bath whose temperature is kept constant or 

 observed very accurately at the moment of the determination. 



If the electrodes are 1 cm apart and have 1 sq. cm surface 

 the conductivity of the solution in reciprocal ohms is the specific 

 conductivity. The specific conductivity divided by the concentra- 

 tion (m) is called the molecular conductivity (X). The usual 



