1915] Arthur W. Thomas 387 



maltodextrin-a of Ling and Baker/ ^ the achroodextrin II of Lint- 

 ner/^ and the maltodextrin of Brown and Morris. ^'^. This proto- 

 dextrin was f urther hydrolyzed by malt extract ; and, by a similar 

 process, another dextrin was isolated from the hydrolytic products. 

 This dextrin was termed y-maltodextrin. By analysis and depres- 

 sion-of-the-freezing-point-measurements, its elementary constitu- 

 tional formula was determined to be C24H42O21. Synkiewski 

 Claims that this dextrin is identical with the maltodextrin-jS of Ling 

 and Baker, and the achroodextrin of Prior.^^ Its formation from 

 protodextrin II is represented by the equation 



^ZQ^Q2^Z1 ~r H2Ü~^ ^24^42^21 "T" ^12ll22^11 



Hydrolysis of this maltodextrin yields the isomaltose of Lintner. 



Protodextrin I was prepared and isolated in a manner similar 

 to that for protodextrin II, with the exception that the malt extract 

 acted in the cold. The molecular formula was found to be 

 C72H124O62 or just twice that of protodextrin II. Hydrolysis of 

 this substance by malt yielded a sugar with the same formula as 

 maitose, but, because of its higher optical rotation and lower re- 

 ducing power than maitose, it was believed to be a polymer of the 

 latter sugar and received the name " dextrinose." 



The next part of this author's investigations consisted in the 

 study of soluble starch (prepared by heating starch paste in an auto- 

 clave under pressure) or, as he called it, amylodextrin. He deter- 

 mined its formula tobe (C54H90O44)» + I" H2O; and, by means of 

 acetylation, found it to contain thirty hydroxyl groups. Years ago 

 Schützenberger and Naudin^^ analyzed an acetyl derivative of ordi- 

 nary starch, with results, according to Synkiewski, that demonstrated 

 the presence in ordinary starch of twenty-seven hydroxyl groups. 

 Since the formation of maitose from this thirty-hydroxyl amylo- 

 dextrin is complete, and since the hydrolysis of ordinary starch 

 stops before all of it is converted to maitose, he concludes that the 

 amylogen residues of the starch molecule (each of which contain 



^8 Ling and Baker: Jour, Chem. Soc, 1897, Ixxi, p. 517. 



19 Lintner : Zeitsch. f. d. ges. Branw., 1894, p. 339. 



20 Brown and Morris : Jour. Chem. Soc, 1885, xlviii, p. 527. 



21 Prior: Bayr. Bierbr., 1896, p. 157. 



22 Schützenberger and Naudin : Ann. Chem., 1871, clx, p. 77. 



