The Oxidation of Cane Sugar. 215 



He dissolved 

 200 grammes of sugar-candy in 2 litres of water, and 

 200 grammes of potassium permanganate in 4 litres of water. 

 These solutions were then mixed and stirred. The temperature 

 rose 20°C. and the liquid gelatinized. The filtrate was neutral ; 

 and on the strength of a few qualitative tests he claimed the 

 discovery of these two new acids. 



The latter name, "trigenic," had, however, been applied by 

 Liebig and Wohler before the year 1850 {Annaien, 59, p. 296), 

 to an entirely difierent compound, C4H7N3O2, which is also known 

 as ethylidene biuret. 



In a later paper {Compt. Rend., 120, p. 783) he says that if 

 the precipitated oxide, which is either MngOg, or a mixture of 

 MnO.2 and MnO, be kept for several days in contact with a 

 strong solution of sugar the brown colour will disappear and 

 hexepic acid (CeHiaOg) be produced. But he explains the failure 

 of other chemists to obtain these acids by the fact that if excess 

 of IMnoOg be pi-esent then in time they become further oxidised 

 to form lactic and formic acids. 



Heyer {Arch. Pharm. [3] 20, p. 430, and Chem. Soc. abstracts, 

 1882, p. 1041) has repeated the experiments of Maumene and 

 other observers. He also employed strong solutions and found 

 that one equivalent of sugar does not react completely in the cold 

 with 4 equivalents of KMn04, oxalates and formates being 

 obtained ; if 12 equivalents of KMn04 be employed then formates 

 and carbonates, but no oxalates are formed. 



C\,H.3,0ii + 1 2KMnO, = 6KHC0, + 6KHC0, + 12Mn0.2 + 5H,0. 



He says that Maumene's " hexepate " was really oxalate, and 

 his " trigenate " was possibly a mixture of acetates and formates 

 of potassium. 



Heyer also repeated Langbien's experiments and found that 

 sulphuric acid intensified the reaction ; whilst if sufficient acid 

 were present, then a manganese salt, and not one of the oxides, 

 was produced. Also the higher the temperature and the greater 

 the amount of KMnO^ present, the more sugar is completely 

 oxidised to carbonate. 



Laubenheimer {Chem. Soc. abstracts, 1873, p. 46) obtains a 

 similar result for the oxidation of Lactose by warm alkaline 

 solutions of permanganate — CO., and MnO.^ being the products. 



