Oxidizers in the Hydrolysis of Starch and Dextrins. 399 



the decomposition of the amidulin molecule once started, the 

 residue may quickly undergo hydrolysis. No attempt has, as 

 yet, been made to discover such an acid, since its formation 

 must be but slight. Some indirect experiments bear weight 

 upon the question. 



1st. A starch solution was digested to the erythrodextrin 

 stage and somewhat beyond by saliva. A test for sugar with 

 5Qcm3 f Fehjjng'g solution resulted in a heavy reduction. 



2d. Into 25 cm3 of impure starch solution iodine was run in 

 regular titration with 50 cm3 of arsenite. An abundance of red 

 was produced. The solution was precipitated by silver nitrate 

 to get rid of potassium iodide and most of the arseniate. The 

 excess of silver nitrate was precipitated by hydrochloric acid. 

 The filtrate was made just alkaline and was added to 50 cm3 of 

 boiling Fehling's solution. There was no sign of reduction, 

 which goes to show that whatever sugar was produced in the 

 hydrolysis of the amidulin impurity in the starch to erythro- 

 dextrin must have been oxidized. In corroboration of this 

 view of the oxidizing effect of iodine in initiating the hydrol- 

 ysis may be mentioned again the action of hydrogen dioxide 

 and potassium permanganate in the presence of acid potassium 

 carbonate upon impure starch and upon amidulin in forming 

 erythrodextrin. 



Somewhat similar to the nascent action upon amidulin of 

 the oxygen produced by iodine in oxidizing arsenite seems to 

 be the action of the oxygen produced in the following phe- 

 nomena. Fr. Goppelsroder* claims that many salts hinder the 

 starch iodide reaction, e. g., potassium alum, ammonium, potas- 

 sium, sodium and magnesium sulphates. As the color, the 

 most important feature for our consideration, slowly develops 

 in his experiments, he mentions it as a reddish tinge, reddish 

 violet cast, bright red violet, etc. He produced his iodine by 

 mixing dilute solutions of potassium iodide, ammonium nitrite, 

 or potassium nitrite, and sulphuric acid with his starch and salt 

 solutions. The iodine was freed by the oxidation of the potas- 

 sium iodide by the nitrite. Here also are conditions, resulting 

 in the presence of nascent oxygen from the nitrite, which in 

 the presence of acid as a hydrolytic agent may have attacked 

 even the starch, thus setting up the hydrolysis which formed 

 erythrodextrin. Very dilute sulphuric acid in the cold > has 

 little effect of itself on starch or dextrin, and the slight amount 

 of erythrodextrin produced, as indicated by the colors men- 

 tioned, would suggest the possibility that amidulin was present 

 in the starch used, as an impurity. 



It remains to thank Professor Gooch for his many useful 



*Ahb. Phys., ccix, 57. 



