between Metals and Dissolved Halogens. 



249 



Temperature 



Table VIII. 

 Mercury and Bromine. 

 400 g. KBr per liter. 



r=240. 



At 



min. 



v 



cc. 



K' 



K 



2. 



0-03133 



0-03133 



0-02658 



0-02630 



0-02188 



0-02162 



0-01780 



0-01759 



0-01434 



0-01416 



0-01142 



0-01126 



0-00900 





0-02919 



0-02919 



0-02494 



0-02469 



0-02047 



0-02025 



0-01654 



01634 



0-01330 



0-01313 



0-01060 



0-01046 



0-00832 





500 

 480 

 460 

 440 

 420 

 400 

 380 



500 

 480 

 460 

 440 

 420 

 400 

 380 



(15-77) 



(11-22) 



16-93 



12-23 



17-10 



12-26 



17-14 



12-18 



17-19 



12-11 



17-03 



11-88 



Av. 



12-13 



(15-08) 



(10-53) 



17-22 



12-52 



17-79 



12-95 



17-27 



12-31 



17-13 



1206 



17-32 



12-17 



Av. 



12-40 



Owing to the method by which they were obtained these 

 constants are necessarily somewhat more uncertain than the 

 iodine constants. A comparison between the two is rather 

 unsatisfactory on account of the presence in both cases of the 

 large excess of soluble halide, and of the pronounced effects 

 which the potassium iodide, and presumably also the potassium 

 bromide, exert upon their respective reaction velocities. In 

 Table I, experiment 8 is the one which approximates most 

 closely to the conditions of the bromine experiments. If we 

 take equal concentrations of the potassium halide as the basis 

 of comparison, we must allow for the fact that the halide con- 

 centration was not the same in the two cases, but was greater 

 in the bromine experiments in the ratio 166/119. Upon the 

 assumption, based on the results of Table I, that a doubling of 

 the concentration of the potassium iodide increases the constant 

 by about ten per cent, the value of the iodine constant, at the 

 same halide concentration as the bromine experiments, would 

 be about 11*0. So compared, the reaction between mercury 

 and bromine would appear to be about twelve per cent more 

 rapid than that with iodine. 



As an example of a reaction of a somewhat different type 

 the rate of solution of mercury in cupric bromide was also 

 determined. The presence of a sufficient quantity of potassium 

 bromide was found to effectually prevent the formation of 



Asi. Jour. Sci. — Fourth Series, Vol. XXIX, No. 171.— March, 1910. 

 17 



