Oxidizers iii the Hydrolysis of Starch and Dextrins. 391 



and by the color of the filtrate, which was yellow. This latter 

 fact showed that the dextrins present, if such they were, had 

 been included in the starch blue. An attempt to wash them 

 out with water completely failed. The principle suggesting 

 this and the following experiment was the greater solubility of 

 the dextrin iodide than of the starch iodide, and the fact that 

 it is not precipitated by dilute sulphuric acid, when alone. 



II. With care iodine was run in just sufficiently to use up 

 the starch present with but the barest excess, so as to include 

 no dextrin iodides if possible. The starch iodide was then 

 precipitated with dilute sulphuric acid and filtered. That 

 there was no excess of free iodine was shown by the lack of 

 action on the filter paper and by the color of the filtrate, which 

 at first came through of a pale blue color and finally came 

 colorless. The precipitate was well washed. To a few cubic 

 centimeters of the filtrate a drop of iodine was added, and at 

 once a red color was produced with no trace of blue. Enough 

 dextrin was present to completely hide the pale blue of the 

 earlier portions of the filtrate. 



This pale blue compound, though separated in less quantity, 

 proved to be the more interesting body, for to it was due the 

 loss of iodine in titration. No method was found, however, of 

 separating it from the erythrodextrin, though its distinct char- 

 acter is shown by the following experiments. A few cubic 

 centimeters of the filtrate above mentioned were colored deep 

 red with iodine, and separate portions were shaken with chloro- 

 form, carbon disuiphide, and amyl alcohol. At once these sol- 

 vents became colored with free iodine respectively purple, 

 purplish red, and yellow, and the watery solution of the dex- 

 trins was left of a pale blue color, proving that the dextrin 

 coloring blue had a stronger affinity for the iodine than the 

 dextrin coloring red. A drop of iodine added to the water, 

 without shaking, colored it red, showing that the erythrodex- 

 trin was still present in the water, i. e. the blue-coloring dextrin 

 held the iodine from the erythrodextrin. 



The next noticeable and interesting feature about this blue- 

 coloring dextrin is its difference from starch in that its iodide is 

 not precipitated either by dilute or concentrated sulphuric acid. 

 Hence this body seems to be intermediate between starch and 

 erythrodextrin ; first, because its iodide is more stable than 

 erythrodextrin iodide ; and second, because its iodide is more 

 soluble than starch iodide. 



Examination was made of the amorphous amylodextrin solu- 

 tion, and of the amidulin solution, since these were bodies 

 coloring blue with iodine and probably intermediate between 

 pure starch and erythrodextrin. 



The amylodextrin iodide blue was readily precipitated by 



