23S Van Name and Edgar — Velocities of Certain Reactions 



of the diffusion theory, and the results have proved to be in 

 agreement with its requirements in all essential details. A 

 similar field was covered by the work of Schiikarew,* in 1891, 

 on the reaction velocities between metals and halogens, 

 but the failure to provide for effective and constant stirring 

 renders Schukarew's results uncertain. So far as known to the 

 present writers, a few experiments by Brunner,f on the rate of 

 solution of pure electrolytic zinc in iodine, constitute the only 

 real test of the validity of the diffusion principle for a reaction 

 between a halogen and a metal, of which an account has been 

 published up to the present time. Brunner does not give his 

 results in detail but found the theory confirmed, especially in 

 the fact the velocity constant agreed with that for the elec- 

 trolytic reduction of iodine. 



Apparatus and Method. 



For all of our experiments the apparatus shown in the figure 

 was employed. The liquid, an aqueous solution of iodine or 



m, metal disk, 

 s, speed indicator. 



bromine with a large excess of the corresponding potassium 

 halide, was contained in an ordinary beaker of about ll'5 cm 

 ^Zeitschr. pliys. Chem., viii, 76. flbid., li, 99. 



