122 Mr. J. J. Hood on the Laivs 



In the experiments referred to, no account was taken of the 

 hydric sulphate present in the solutions, it being merely stated 

 that an indefinite quantity was employed. As this reaction 

 seems likely to lead to some interesting facts regarding the 

 effect of salts on rate of oxidation and the like, I have thought 

 it advisable to study first the result of a variation in the amount 

 and quality of the acid, in order to ascertain in what manner 

 the constants in the above equation are connected with the 

 conditions of experiment. 



The equation y (a + t)=b was established on the supposition 

 that the amount of change in a unit of time was proportional 

 to the product of the active bodies ferrous iron and potassic 

 chlorate, and that these were in " equivalent"" proportion 

 according to (1). 



Since hydric sulphate takes an active part in the oxidation, 

 we may suppose from analogy that the amount of change in 

 unit of time is proportional to the product of all three sub- 

 stances, viz., the iron (A— a), the potassic chlorate (B — /3), 

 and the hydric sulphate (C — y), where A, B, C are the quan- 

 tities of these bodies at the commencement of the action, aj3y 

 the amounts that have suffered decomposition up to any time. 



Consequently the equation representing this hypothesis 

 will be j„ 



g=A (A-«) (B-/3) (0- 7 ). ... (2) 



Taking the chemical equation to be 

 6 FeS0 4 + KC10 3 + 3 H 2 SO,= 3 Fe 2 (S0 4 ) 3 + KC1 + 3 H 2 0, (3) 

 for equivalent quantities the following ratios will hold : — 



-— = — = — (constant); 



7 V 



If, however, the acid be in large excess, say n times that 

 required by (3), it may be considered to undergo comparatively 

 little change. Treating it as constant and equal to nv'A, (2) 

 becomes 



^=WnA(A- a ) 2 ; 



replacing (A — a) by y the residue of unoxidized iron, and 

 integrating, 



v'nA — y \kvv f nK +t ) 



Icvv'nA 



Writing this equation in the more convenient form 

 b=y (a + t), 



