Potassium Permanganate and Sulphuric Acid. 305 



the first five experiments of series B the proportions of acid 

 and liquid of series A were preserved while the absolute vol- 

 umes were increased ; in the last four experiments the range 

 of variation in proportions was extended. 



Table II. 



H 2 S0 4 

 [1:1] 



Water. 



K 2 Mn 2 8 in 



decinormal 



solution. 



Percentage of 

 HnS0 4 [1:1] 

 in solution 

 during action. 



Percentage of 



K 2 Mn 2 8 used 



as compared 



with that required 



by theory. 



cm 3 



cm 8 



'cm 3 

 A. 

 Treated at 



once. 







2 



8 



10 





10 



100 



4 



6 



10 





20 



100-2 



6 



4 



10 





30 



100-1 



8 



2 



10 





40 



100-1 



10 





10 



B. 

 Treated at 



once. 



50 



100-3 



10 



80 



10 





10 



100-1 



20 



70 



10 





20 



100-1 



30 



60 



10 





30 



100- 



40 



50 



10 





40 



100-5 



50 



40 



10 





50 



101-3 



60 



30 



10 





60 



103- 



70 



20 



10 





70 



105- 



80 



10 



10 





80 



103-3 



90 



.. 



10 





90 



108-1 



The results, of these experiments indicate, as was antici- 

 pated, that rather less decomposition of permanganate is 

 caused by the sulphuric acid when the reduction of the re- 

 sidual permanganate is effected at ordinary temperatures. The 

 increase in the amount of decomposition as the proportions of 

 sulphuric acid [1 : 1] present are pushed beyond fifty per cent 

 of the liquid is striking. 



We have studied these same phenomena still further, vary- 

 ing, however, the mode of proceeding so as to observe and 

 measure the gas evolved from the liquid as Jones* and Brauner* 

 did in their individual investigations of the evolution of oxy- 

 gen during oxidations. In these experiments tubes of suitable 

 size and length, holding from 100 cm 3 to 200 cm 3 , were sealed 

 at one end, filled completely with the mixtures of acid and 

 permanganate, inverted, and allowed to stand with the lower 

 and open end submerged in liquid of the exact composition of 

 that which filled them. The details and results of these 

 experiments are recorded in Table III. 



* loc. cit. 



