380 Chemical Constitution of Starch [June-September 



the molecular size (Ci2H2oOio)6' thus corroborating the work of 

 Musculus. 



Herzfeld,^ while not contributing directly to the knowledge of 

 the size of the starch molecule, started a new line of thought, in 

 which he pointed out that the hydrolysis progressed through a 

 series of dextrins of diminishing complexity before, or in the 

 course of, the conversion of starch to sugar, i. e., starch, to soluble 

 starch, to erythrodextrin, to achroodextrin, to maltodextrin, finally 

 to maitose. To maltodextrin he assigned the formula C18H36O16. 

 The discovery of maltodextrin was quite a significant step, for all 

 subsequent work has depended on the study of just such substances 

 — substances which combine the properties of sugar and of dextrin. 



Brown and Heron® found that the hydrolysis of starch by malt 

 stopped when four fifths of its weight of maitose was formed, the 

 remaining one fifth consisting of a dextrin. They accepted the 

 theory of Musculus and Grueber, and of Herzfeld, that starch was 

 hydrolyzed in successive steps to dextrin and to sugar. From their 

 experiments with malt diastase they concluded, most naturally, that 

 the starch molecule must be at least five times the size of the residual 

 dextrin, and proposed (Ci2HooOio)io as the formula for starch, 

 the simplest dextrin molecule being thought to be (Ci2H2oOio)2- 



In 1885, Brown and Morris^ reported that a dextrin was always 

 present as one of the hydrolytic products of starch, which, while 

 not identical with the maltodextrin öf Herzfeld, bore a resemblance 

 to it. They assigned to this Compound the formula (Ci2H2oOio)2* 

 C12H22O11. Inasmuch as this dextrin was difficult to hydrolyze 

 they gave starch the formula 5(Ci2H2oOio)3, in order to make it 

 agree with the principles evolved from their earlier work. The 

 (Ci2H2oOio)3 group was called amylin, the starch molecule con- 

 sisting of four such groups arranged symmetrically about a fifth. 

 Upon hydrolysis an amylin group was thought to split off as malto- 

 dextrin, leaving the other four as a more complex dextrin, the 

 maltodextrin in turn Splitting directly into maitose. 



Brown and Morris^ determined the molecular weight of amylin 



5 Herzfeld : Berichte, 1879, xii, p. 2120. 

 ß Brown and Heron : Arm. Chem., 1879, cxcix, p. 165. 

 "^ Brown and Morris : Ann. Chcm., 1885, ccxxxi, p. 72. 



8 Brown and Morris: Jour. Chcm. Soc, 1889, Iv, p. 96; Berichte, 1891, xxiv, 

 p. 723- 



