458 



Messrs. S. E. Sheppard and C. E. K. Mees. [Dec. 20, 



Tested experimentally, the first series gave a decreasing value for 

 K. It was found that this was due to the accumulation of bromide, 

 which lowered the velocity. This was avoided by adding excess of 

 free bromide in such quantity that the amount due to development 

 was negligible. 



The following series give some of the results : 



Table IV. 



K - 



Series I. 



Series II. 



Mean... K = 0-01995. 



Mean... K =-- 0-0194. 



Series III. 



Series IV. 



Time. 

 5-0 mins. 

 10-0 

 15-0 

 20-0 

 25-0 



00 



Density. 



0-311 



0-838 



1-000 



1-266 



1-401 



2-053 



K. 



0-0149 

 0-0229 

 0-0193 

 0-0208 

 0-0199 



Mean... K = 0-01992. 



Total mean of four series 



The developer was 



Time. 

 5'0 mins. 

 10-0 

 15-0 

 20-5 

 25-0 

 30-0 

 45-5 



00 



Density. 



0-283 



0-547 



0-759 



0-919 



0-990 



1-114 



1-276 



1-437 



K. 



0-0190 

 0-0208 

 0-0217 

 0-0214 

 0-0203 

 0-0217 

 0-0209 



Mean... K = 0-0208. 

 K = 0-0203 



4-00 c.c. FeS0 4 mol. 



2-00 KBr, N/10 



40-00 K 2 C 2 4 mol 



IIM 



>- 



= N/25. 

 N/500. 



To 100-0 c.c. with H 2 0. 



