ERYTHRODEXTRtN, ACHROODEXTRIN, GRENZDEXTRIN, ETC. 137 



u. d. Fort. d. Thierchemie, 1903, xxxiii, lOG) ascertained that precipitation of the products 

 of digestion by an aqueous solution of barium hydroxide does not throw down aclu-oodex- 

 trin, while with an alcohohc solution of barium hydroxide the achroodextrin can not be 

 separated from the ery throdextrin ; but by precipitating the amylodextrin and erythro- 

 dextrin with an aqueous solution, and subsequently the achr-oodextrin in an alcoholic 

 solution, the dextrin may be separated, and also a minute quantity of an undetermined 

 dextrin-like substance. Repeated precipitation with barium hydroxide was found to free 

 the dextrins from adherent sugars. Prolonged digestion of starch always gave a residue 

 that was not starcli, dextrin, or cellulose. According to Moreau, dextrins do not exist as 

 such in the starch molecule, nor are they produced by boiling a 1 per cent starch-paste, 

 as maintained by Griessmayer. Moreau is of the opinion that Griessmayer's results were 

 due to the presence of micro-organisms. 



In order to avoid misunderstanding in the use of terms applied to the intermediate 

 products of the saccharification of starch. Ling (Jour. Fed. Inst. Brewing, 1903, ix, 446) 

 proposes to discontinue the use of the word dextrin as applied to the products of diastatic 

 and acid digestion, and substitute the word maltodextrin, which he thinks would not only 

 specifically indicate the mode of origin, but also distinguish those products from torrefac- 

 tion dextrin. 



Achroodextrin was prepared from peat, lichens, and moss by Reynaud (Jour. Soc. 

 Chem. Industry, 1903, xxii, 567). A comparison of the products of potato starch with 

 those of cereal starches was made by O'Sullivan (Proc. Chem. Soc, 1904, xx, 65), who 

 states that no quantitative relationships were found between the percentages of maltose 

 and dextrin of the former with those of the latter (see p. 148). 



The rapidity of hydrolysis by the action of dilute acids upon dextrin and maltose 

 was studied by Noyes and several associates (Jour. Amer. Chem. Soc, 1904, xxvi, 266), 

 who recorded that dilute liydrochloric acid will hydrolyze dextrin only half as rapidly as 

 it will maltose. A 2.5 per cent hydrochloric acid hardly affected tlie reducing power of 

 dextrin, but the hyth-olysis of maltose at 100° reached 90 per cent in an hour, and somewhat 

 less than 95 per cent in 2 hours. 



The behavior of starch, amylodextrin, and erythrodextrin towards chromic acid was 

 investigated by Harz (Beiheft. z. Botan. Centralbl., 1905; Woch. f. Brau, 1905, xxii, 721). 

 The author states that chromic acid forms combinations with these three substances that 

 are analogous to those formed by iodine; and that all three behave in such a way as to indi- 

 cate that not one is a uniform substance, and that they really consist of a munber of groups 

 which differ in density or complexity of their molecular structures. Achroodextrin seemed 

 to be of apparently uniform composition. 



The method employed by Biilow (p. 130) for the separation of the several products 

 of digestion by aqueous and alcoholic solutions of barium hydroxide was improved by 

 Moreau (Ann. d. d. Soc. roy. Sc. med. nat. d. Bruxelles, 1905; Woch. f. Brau, 1905, xxii, 

 37). The progress of the reaction was determined by iodine. He found that amylodextrin 

 and erythrodextrin were precipitated from aqueous solutions, but not achroodextrin or 

 sugar, both of which were precipitated in the presence of alcohol. The limits of pre- 

 cipitation were sufficiently far apart to permit of a complete separation of the several 

 constituents by successive fractional precipitation by barium hydroxide. By this 

 method he found in the digestion of starch by diastase, ptyalin, pancreatin, serum, or 

 mineral acids that even during the very earliest stages of the decomposition processes 

 all three forms of dextrin, as well as sugar, were present. He states that this confirms 

 Mittehnayer's theory of starch conversion, that is, that the starch molecule is at once 

 broken down into these products, and that there may be some subsequent hydrolysis of 

 the dextrins first formed. Moreau gives in detail processes for preparing amylodextrin, 

 erytlu'odextrin, and achroodextrin from commercial dextrin. The first two he prepared 



