Electrode^ 



^Mercury in 

 ^lass tube 



Pyrex 

 test-tcjt)c> 



'Cement 



.Electrode 



Fig. 1. Type of conductivity cell used. The cell consists of a Pyrex test-tube 

 of about 40 cc. capacity and 20 mm. in diameter. The electrodes are made of 

 No. 20 platinum wire sealed into fine Pyrex glass tubing. The electrodes are 

 plated with platinum black and are 5 mm. long. The tubes holding the electrodes 

 are fastened to the sides of the test-tube with de Kotynsky cement and are then 

 filled with mercury. The distance between the electrodes is so adjusted that 

 all the cells have the same constant; i.e., when filled with the same solution they 

 all read the same. 



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