of Chemical Change. 449 



results, however, obtained for these salts, to be found further 

 on, being of a rather anomalous character, the influence of 

 sulphates was made the subject of a long series of experiments, 

 the results obtained being contained in Table I. 



Each experimental solution had a volume of 110 cubic cen- 

 tims., and contained '3736 gram Fe /X as chloride, and 1*321 

 gram free HC1. To this was added 25 cubic centims. KC10 3 

 solution, equal to '3406 gram, making the total volume =135 

 cubic centims., care being taken to have the solutions at the 

 same temperature before mixing. From such a solution 10 

 cubic centims. were withdrawn, run into a small flask contain- 

 ing a few cubic centimetres of a nearly saturated solution of 

 MgS0 4 *, and titrated with permanganate. 



The chemical conditions represented by these quantities of 

 materials are 



6 FeCl 2 + (2-5)KC10 3 + 6(5-425 )HCL 



The value for A w r as determined by diluting 10 cubic cen- 

 tims. of the stock solution of ferrous chloride (='3736 gram 

 Fe") to 135 cubic centims., and titrating 10 cubic centims. of 

 this wdth the permanganate, the number of cubic centimetres 

 required being taken as equal to 10*5, the value for A ; but 

 although only approximately of this strength, the usual pro- 

 portional corrections were made on the values for y for each 

 experiment ; in which way all the experiments are rendered 

 comparable with each other, as if performed with the same 

 standard solution of permanganate. 



Inserting these values of v x = 2*5, r 2 = 5*425, and A = 10*5 

 in equation (3), it becomes 



s( a 40*1 y + 15-75 - K1 y + 46-46\ ■ ■ /K . 

 /(4-4251og 10 ^— ^ l-51og 10 *— )=ff + t. (5) 



The following three experiments will illustrate this formula, 

 and how r the retardation-effects are determined with magnesic 

 sulphate as the retarding agent. Employing the first and 

 third observations, the values obtained for /and g in equation 

 (5) are 115*1 and 77*2 respectively; and side by side with 

 the observed values for t are the calculated quantities. 



* Besides tending to stop the reaction, the addition of MgS0 4 , the 

 author has shown (Chemical News, vol. 1.), renders the estimation of iron 

 by permanganate in presence of free hydric chloride perfectly reliable. 

 Mr. W. H. Deering has drawn attention to the fact that Zimmermann 

 had previously proposed MnS0 4 for the same purpose. 



