﻿i9i6] REED-OXIDATION POTENTIAL 525 



about 50 cc. capacity, platinized on both sides in the ordinary 

 manner, and completely submerged in the solution. The other 

 half of the cell was a standard calomel electrode (C) made up in a 

 150 cc. bottle with saturated KC1. To prevent contamination by 

 diffusion of the reaction mixture into the electrode, connection was 

 made by means of a siphon to a bottle (D) containing saturated 

 KG; and from this, by means of a second siphon, connection was 

 made with the reaction cell A. To further prevent diffusion, this 



second siphon contained a cotton wick for a part of its length, and 

 was kept closed by means of a pinchcock (on a rubber section of 

 the siphon), and finally terminated in a fine capillary which dipped 

 into the reaction mixture. The reservoir of saturated KC1 at E 

 allowed the capillary to be washed out frequently without dis- 

 turbing the electrode. 



Measurement of the total potential of the cell (that is, the 

 potential at the platinum electrode plus the known potential of the 



