Oxidizers in the Hydrolysis of Starch and Dextrins. 397 



10th. Erythrodextrm is the first product of hydrolysis of 

 amidulm, and since erythrodextrm was proven to be present in 

 the impure starch it is probable that the blue-coloring compound 

 is identical with amidulm from which erythrodextrm is formed. 



So it appears that the colors found in iodometric titrations 

 in which ordinary starch is used as an indicator are probably 

 due to the admixtures of the starch blue or possibly of the 

 amidulin blue with the red of erythrodextrm derived from 

 amidulm by hydrolysis initiated by the oxidizing effects of the 

 iodine. Pure starch, containing neither amidulin nor erythro- 

 dextrm, gives only blue in the iodometric titration. Starch, on 

 the other hand, which has undergone partial hydrolysis is likely 

 to contain both amidulin and erythrodextrm. It is not 

 strange that both amidulin and erythrodextrm should be 

 present as impurity in starch since they both stand in the 

 order named as the first two dextrins produced from starch, as 

 shown by saliva digestion of starch, as also by malt-extract 

 digestion of starch. Starch both in solid state and in solution 

 tends to pass through these stages of hydrolysis. Germ 

 growth rapidly appears in solutions of pure amidulin and pure 

 erythrodextrm with the destruction of these bodies in the 

 form of hydrolysis to dextrins lower in the series. Some dry 

 pure starch, which stood in a cardboard box during the sum- 

 mer, shows the tests for a slight amount of amidulin ; some 

 dry amidulin, wrapped in filter paper, has gone over .to erythro- 

 dextrm almost entirely. 



A few words may be said in closing this article on the 

 mechanism of the reaction which is believed to take place. 

 The production of the various dextrins from starch is com- 

 monly considered a progressive hydrolysis. Associated with 

 the formation of erythrodextrm from amidulin during oxida- 

 tions by iodine there is a loss of iodine, and this loss would 

 naturally be attributed to oxidation of amidulin. That the 

 hydrolysis of amidulin to erythrodextrm can take place, how- 

 ever, without oxygen is evident from the fact that amidulin or 

 erythrodextrm may be produced successively by digesting 

 starch with saliva in an atmosphere of hydrogen ; for two such 

 digestions were carried on, all oxygen being previously boiled 

 out of the starch solution and a current of hydrogen passed in 

 during the digestion. The question arises, then, as to why the 

 hydrolysis, which acid potassium carbonate even upon boiling 

 is incapable of producing, takes place readily in the presence 

 of an oxidizer. There are present in starch and the dextrins 

 several sugar nuclei, and, in the formation of dextrins, maltose, 

 and sometimes isomaltose, is said to be formed in increasing 

 quantity as the dextrin molecules decrease in size. Maltose is 

 readily hydrolyzed to dextrose, and dextrose is fairly easily 



