RICHARDS AND ARCHIBALD. — CONCENTRATED SOLUTIONS. 361 



the tendency to form complex compounds is much less than that 

 exhibited by chlorides ; hence the Latimer-Clarke and Weston cells are 

 not much affected by this type of side-reaction. 



The results of the present paper may be stated briefly as follows : — 



1. The action of dissolved chlorides upon calomel is not catalytic, but 

 results in the establishment of a definite equilibrium. 



2. With equivalent solutions, less concentrated than five times nor- 

 mal, hydrochloric acid and sodic chloride have about equal tendencies to 

 effect the reaction ; baric chloride has less tendency, calcic chloride still 

 less, and cadmic chloride no appreciable tendency. 



3. The extent of the reaction in solutions not too concentrated is 

 approximately a simple function of the square of the concentration of the 

 chloride ion. This relation, taken in connection with a number of other 

 considerations, points to the existence of a highly ionized complex 

 HgCl/' in the solution, and thus confirms the work of Le Blanc and 

 Noyes. 



4. If approximate allowance is made for the probable concentration of 

 undissociated complex salt present, all the figures, even as far as ten 

 times normal solutions, seem to be explicable. 



5. The suggestion is made that the reaction may be of use as a 

 means of determining the concentration of the chlorine ion. 



6. The corresponding reactions are much less marked with sulphates, 

 but much more so with bromides and iodides. 



7. Caution is needed when using mercurous chloride as a means of 

 determining mercury in quantitative analysis. 



Cambridge, 1899-1901. 



