The Oxidation of Cane Sugar. 221 



(ii.) the concentration of the solutions, 



(iii.) the temperature of experiment, 



(iv.) the time of the experiment, 

 and finally, to decide what was the shortest time in which the 

 reaction could be made to complete itself under suitable and 

 convenient conditions. 



(b) Experimental Methods. 



An attempt was made to titrate a known amount of sugar 

 with a standard solution of KMn04. 



Sugar solutions, even if very dilute, were found in the 

 presence of dilute acids (sulphuric was used) to readily reduce, 



N ^ 

 i.e., decolorize, a few drops of ftv KMn04 solution, on boiling. 



N ^ 

 But when about I'TSccs. ^^ KMnO. had been added in this 

 50 



way to lOccs. of — — -r Sugar solution in a flask, the brown 



precipitate which was formed would no longer dissolve, and 

 after nearly 5ccs. of the permanganate solution had been added, 

 its pink colour permanently remained even on continued boiling. 

 Excess of acid did not influence this result. 



Nearly 10 equivalents of KMn04 had been added to each 

 equivalent of sugar, but as 9-6 KMn04 is required for complete 

 oxidation of sugar, if itself entirely reduced to MnS04 as 

 apparently was only the case at first, then all the sugar could not 

 have been oxidised to carbonic acid, and probably some was only 

 oxidised to the condition of oxalic or formic acids, or a still lower 

 state of oxidation. 



Direct titration not being possible, it was evident that 

 practically only three methods of following the course of the 

 reaction were available. 



(i.) Estimation of the carbonic acid, produced by the 

 oxidation of a known weight of sugar, by 

 absorption in soda-lime tubes or otherwise, as 

 in organic analysis, 

 (ii.) Some modification of the "Forchammer" or 

 "Oxygen" process, which is used for esti- 

 mating organic matter in potable and other 

 waters. 



