RICHARDS. — CALOMEL ELECTRODE. 



13 



the extremities of the box gave a difference of potential of just 0.1000 

 volt. This potential was verified and adjusted from day to day by means 

 of a suitably connected Helmholtz one-volt cell, which in its turn had been 

 compared with several standard Clark and Weston cells. The " gravity " 

 cell remained admirably constant in potential. 



The measm-ements involving decinormal solutions are the most accu- 

 rate of those given below. The resistance of the centiuormal solutions 

 tended to diminish the accuracy with this dilution, because the galvanom- 

 eter became ineffective ; while the formation of mercuric chloride made 

 uncertain the very easily measured potential of the normal solution. 

 Many of the figures, especially those referiing to normal hydric, sodic, and 

 potassic chlorides, represent determinations made from a number of solu- 

 tions of substances prepared in different ways; since these always gave 

 the same result, only one figure is given for each. 



SERIES VI. 



Chlorides between 0° and oO°. 



Including a larger number of Electrolytes. Cell = Hg - HgCl - MC1„ - HgCl - Hg. 



* This result is somewhat lower than that obtained by Coggeshall and others, 

 but since I repeatedly obtained it, I cannot but believe that otlier results must have 

 been complicated by some modifying circumstance. See Z. Phys. Chem., XVII. 85. 



