ERYTHRODEXTRCN, AOHROODEXTRIN, GRENZDEXTUIN, ETC. 



135 



of the same (.le.xtriii. In a still later contribution (Compt. rend., 1900, cxxxi, 453) Petit 

 studied the dextrins formed at 50°, 00°, and 70°, respectively, which were separated by- 

 successive precipitations wath alcohol. 



The figures given in table 10 are recorded. 



Table 10. 



The first two he regards as being probably identical, but quite different from the third. 



Differences in the products of diastatic and acid action were recorded by van Laer 

 (Jour. Fed. Inst. Brew., 1900, vi, 162), who notes that not only are the sugar-products 

 not identical, but also the intermediate bodies. (See page 152.) Acetyl derivatives were 

 studied by Pregl (Monatsch. f. Chem., 1901, xxii, 1049), who found a substance that gave 

 a red reaction with iodine, and wliich he believes is an erythrodextrin. It is stated to 

 reduce Fehling's solution and to have a reducing power equal to about 12.5 per cent of 

 that of glucose. He could not identify it with any known dextrin, but states that it resem- 

 bles a dextrin described by Syniewski, which was obtained by the action of malt extract. 



Baker (Join*. Chem. Soc, 1902, xviii, 134) investigated the actions of the diastase of 

 ungerminated barley on soluble starch, in which the reaction was caused to continue for 

 1^2 hours at 50°, when it was found that dextrins and maltose were the only products. 

 One of the dextrins obtained by precipitation with alcohol is recorded as giving a blue 

 reaction \vith iodine and to be acted upon by the barley diastase very slowly. After diges- 

 tion for 90 hom-s at 45° to 50°, the product is stated to yield a blue reaction with iodine 

 and to consist of unaltered dextrin with maltose and glucose. After 18 hours at 55°, by 

 the action of malt diastase, this dextrin no longer gave a blue reaction with iodine, and the 

 products consisted of acliroodextrin and a considerable quantity of glucose. The dextrin 

 formed by barley diastase differed from Nageli's amylodextrin, and he proposes, owing to 

 its general behavior, to name it T-amijlodextrin. 



Erythrodextrin was described by Hale as being one of the products formed by the 

 primary action of iodine and oxidizing agents on starch (Amer. Jour. Science, 1902, xiii, 

 379). By titrating an arsenite or tartar emetic solution with iodine and impure starch, 

 a loss of iodine occurs and a compound forms that gives a red reaction with iodine. This 

 compound behaved like erythrodextrin, but it was not identical with it. Impure starch 

 yielded also another substance which seemed to be intermediate between starch and ery- 

 throdextrin. He states that amidulin stands between soluble starch and erythrodextrin 

 and that the last is the first product of amidulin. 



In a fm-ther report on the constitution and decomposition products of starch, Syniewski 

 (Rozfrawy ahademji umiejetnosci, Krakau, 1902; Jalir. ii. d. Fort. d. Tierchemie, 1902, 

 XXXII, 98, 100) subjected a 5 per cent solution of potato-starch to a temperature of 138° 

 to 140° for 12 hours, and obtained amylodextrin. The hydrolysis of amylodextrin by malt 

 extract at room temperature yielded a dextrin which he named grenzdextrin I. Malt 

 extract acting on this dextrin produced maltose and an isomer of maltose which he named 

 dexirinose. By heating malt extract for 15 minutes and then adding amylodextrin solution, 

 and stopping the action at the point when the solution no longer gave a blue reaction 

 with iodine, the amylodextrin was found to have been converted into a form thstinguished 

 as grenzdextrin II. This he belie\cs is identical with Brown and Morris's maltodextrin, 



