between Metals and Dissolved Halogens. 



247 



so that the rate of evaporation (for constant volume and 

 constant free surface) must be proportional to the concen- 

 tration, and will follow a mathematical expression of the same 

 form as that which holds for the reaction with a metal. To 

 correct the observed velocity constants it is therefore only 

 necessary to subtract from them the velocity constants for the 

 evaporation of bromine, as determined by separate blank 

 experiments under like conditions. 



Temperature 25 c 



Table VI. 

 Evaporation of Bromine. 



400 g. KBr per liter. 



r=240 



C 



At 

 min. 



K" 



0-02882 



0-02767 



0-02418 



0-02322 



0-02027 



0-01946 



0-01707 



0-01639 



0-01434 



0-01377 



0-01218 





003262 



0-03117 



0-02669 



0-02550 



0-02171 



0-02074 



0-01766 



0-01688 



0-01406 



0-01344 



0-01145 



0-01094 



0-009335 





0-03526 



0-03350 



0-02764 



0-02626 



0-02165 



0-02057 



0-01687 



0-01603 



0-01333 



0-01266 



0-01054 





15 

 15 

 15 

 15 

 15 



15 

 15 

 15 

 15 

 15 

 15 



15 

 15 

 15 

 15 



15 



500 

 500 

 500 

 500 

 500 

 500 



450 

 450 

 450 

 450 

 450 

 450 

 450 



400 

 400 

 400 

 400 

 400 

 400 



4-49 

 4-52 



4-37 

 4-44 

 4-09 



Av. 4-38 



4-66 



4-83 

 4-82 

 (5-47) 

 4-81 

 4-75 



Av. 4-77 



Av. 5-06 



In practice the rate of evaporation of the bromine increases 

 as the volume diminishes, owing to the increasing concavity 

 of the surface of the solution caused by the rotary stirrer. 

 The blank experiments recorded in Table VI were therefore 

 carried out at constant volume, which was accomplished by add- 

 ing to the liquid, immediately after withdrawing each sample 

 for analysis, an exactly equal quantity of fresh potassium 

 bromide solution. The resulting bromine concentrations were 

 readily calculated, and are given in the column headed C 7 , 



