392 Hale — Initiative Action of Iodine and other 



4 



dilute sulphuric acid. The amidulin iodide blue was not precip- 

 itated by dilute sulphuric acid nor by concentrated sulphuric 

 acid. Both amylodextrin and amidulin were tried with perman- 

 ganate and acid potassium carbonate with the following results. 



I. In an Erlenmeyer flask 100 cra3 of water, 10 cm3 of acid 

 potassium carbonate, l cm3 of potassium permanganate and 25 cm3 

 of amylodextrin were boiled five minutes. The permanganate 

 faded to a yellow color. The solution was made acid and the 

 excess of permanganate was faded by a few drops of dilute 

 sulphurous acid. The solution was then cooled, made alkaline, 

 and iodine solution was added. Two drops brought out a blue 

 with a trace of purple, due possibly to the presence of a trace 

 of impurity, since the amylodextrin was made from impure 

 starch. 



II. In an Erlenmeyer flask 100 cm3 of water, 10 cm3 of acid 

 potassium carbonate, l cm3 of potassium permanganate and 25 cinS 

 of amidulin were boiled five minutes. A brown precipitate 

 formed and was filtered off. The filtrate was clear and color- 

 less. It was cooled and iodine was added. A deep red color 

 was produced, equal to and identical with the color given by 

 erythrodextrin with iodine. There was a loss of about two 

 drops of iodine. 



Tests were made with amidulin in regular titration. 



Table XI. 

 A 

 Volume, ra/10 As Q 3 . n/10 I sol. KE1C0 3 . Amidulin. Color. 



cm 3 . cm 3 . cm 3 . cm 3 . cm 3 . 



125 50 49-29 5 pale yellow 



135 50 49*40 5 25 deep red, to deep 



purple 



100 2 drops * 25 good deep blue 



100 2 drops _ (lgrm.KI)25 purplish 



Sb 2 3 B 



125 50 4775 25 very pale yellow 



150 50 47-82 25 25 deep red, to deep 



purple 



The two experiments in A in blank show that two drops are 

 necessary for a reading in any case. One gram of potassium 

 iodide, the amount present in an ordinary titration, tended to 

 give a purplish hue to the blue. This is probably analagous 

 to the action of an excess of potassium iodide upon the starch 

 iodide. f Both phenomena seem to be distinct from the 

 hydrolytic action. 



Though the titrations were at a fair dilution, yet the table 

 shows a loss of about 0*08 cm3 of iodine solution. Allowing 



* On addition of acid potassium carbonate the solution turned purplish, and the 

 blue showed a tendency to fade, 

 f See Table I. 



