142 DIFFERENTIATION AND SPECIFICITY OF STARCHES. 



Geduld (Wochensclirift f. Brauerei, 1892, viu, 620) also extracted glucase from corn by 

 soaking the grist in cold water, filtering, and precipitating with alcohol. At temperatures 

 from 57° to 60°, 1 part converted 100 parts of maltose into glucose. This enzyme was pre- 

 pared later by Beijerinck and others. The same or a similar enzyme has been shown to exist 

 in the sera of the blood and lymph, in the saliva and pancreatic juice and succus entericus, 

 and in yeast and malt, and in emulsin and certain other enzymes. Its presence or absence, 

 as well as the amount present, serve at times to explain many discrepancies in the results of 

 various observers as to the kind or kinds of sugar formed. In fact, diastatic enzymes as 

 ordinarily prepared, especially animal enzymes, are apt to contain more or less glucase, and 

 hence to give rise to more or less conversion of maltose into glucose (see page 143). 



Differences in the sugar product by the actions of enzymes and dilute acids, respect- 

 ively, were noted by Effront (Moniteur scient., 1887, 513). He states that maltose is 

 always formed by the actions of enzymes and acids; that in the saccharification by malt 

 the production of glucose is variable; that by the action of acid glucose is alwaj's formed 

 with maltose in the earliest stages; and that in the earliest stages there is produced an 

 almost constant ratio between the percentages of maltose and glucose (34 to 38 of maltose 

 to 100 of glucose). 



Griessmayer (Allgem. Brauer- und Hopfenzeit., 1887, xxvi, 147), in his studies of the 

 nature of the starch-cellulose of C. Nageli, refers to the presence of maltose and glucose 

 after treating starch-grains with dilute acid until the skeleton-like substance (starch- 

 cellulose) remained. Hanofsky (IMittheil. d. k. k. Tech. Gew.-Museums, 1889, 56), in 

 analyses of commercial dextrin, makes note of the presence of maltose and also of the 

 conversion of this sugar into glucose by further action of dilute acid. Brown and Morris 

 (Jour. Chem. Soc. Trans., 1889, lv, 462) refer to maltose as the final product of the action 

 of diastase. Lintner (Brauer u. Malzerkalender, 1890, xiii, 83), in his examinations of 

 the action of diastase on raw starch from different sources at different temperatures, 

 filtered the preparations and changed the dissolved substances into glucose by hydro- 

 chloric acid. Flourens (Compt. rend., 1890, ex, 1204) subjected starch to the action of 

 dilute sulphuric acid and found that the properties of the products of digestion as deter- 

 mined by their rotatory and reducing powers are in accord with the belief that only one 

 dextrin together with glucose is formed, but no maltose. 



The synthesis of a new glucobiose, now known as isomaltose, which is of importance 

 as one of the end-products of the saccharification of starch, was reported by Fischer (Ber. 

 d. d. chem. Gesellschaft., 1890, xxiii, 3687; 1895, xxviii, 3024). This sugar was obtained 

 by subjecting 100 grams of glucose in 400 grams of hydrochloric acid of a specific gravity 

 of 1.19 for 15 hours at a temperature of 10° to 15°. By precipitation with alcohol, a floc- 

 culent deposit was obtained which contained a small amount of isomaltose together with 

 other substances. From the filtrate a precipitate was thrown down by ether, which con- 

 sisted of glucose, isomaltose, and another substance. By appropriate methods isomaltose 

 was isolated and its properties studied. 



A body was prepared by Schiebler and Mittelmeier (Ber. d. d. chem. Gesellsch., 

 1890, XXIII, 3060; 1890, xxiv, 301) from the unfermented residue of starch sugar, which 

 they state is identical with the isomaltose of Fischer that was prepared from glucose by the 

 action of acid. This residue, referred to as galUsin, was purified by repeated precipitation 

 wdth strong alcohol, and they found that it yielded an osazone which resembled the osa- 

 zones of saccharoses, from which they concluded that gallisin contains a sugar. At first 

 it was thought that tliis sugar was an intermediate product between starch-cellulose and 

 glucose, but in their second contribution they recognize that the new sugar is formed 

 from glucose. They subjected glucose to the action of 2.5 per cent sulphuric acid for 

 12 hours on a water-bath. The acid was then gotten rid of bj' barium hydrate, and the 

 solution heated with phenylhydrazine acetate, when a large quantity of glucosone separated; 



