BETWEEN THE CONDITIONS OF A CHEMICAL CHANGE AND ITS AMOUNT. 203 



Table VI. 



K2Mn2 08+3MnS04+5H2C2 04+7iH2S04. 



Volume of solution 330 cub. centims. Temperature 16° C. Time x mins. 



These numbers present a less obvious relation than those of the first series, but it may 

 be observed in all, after the fourth minute, that if the numbers representing the time, 

 minus about one minute, be multiplied into the corresponding amounts of residue, the 

 product is approximately a constant quantity, {x—XQ)y=Jc. But in fact each successive 

 series is less and less conformable to this relation. Probably the increase in the amount 

 of sulphuric acid produces this effect by diminishing the disproportion between the two 

 rates before mentioned, for its action is to retard the formation of manganic binoxide, 

 and to hasten its reduction by oxalic acid. 



With a smaller quantity of sulphuric acid and a larger quantity of manganous sul- 

 phate more satisfactory results were obtained, but it was not found possible, when only 

 a proportional quantity of oxalic acid was employed, to hinder the solution from becoming 

 turbid through separation of manganic binoxide. The use of a large volume of water pre- 

 vents the occurrence of this turbidity, but impairs too far the accuracy of the subsequent 

 determinations. The series of experiments recorded in the following Table traces the 

 course of the reaction with an excess of manganous sulphate, and proportional quantities 

 of each of the other substances, through its entire length. 



Table VII. 



K2Mn2 08+15MnS04+3H2S04+5H2C2 04. 



Volume of solution 100 cub. centims. Temperature 16° C. Time x mins. 



2f2 



