THE AMYLOSES. 189 



and Morris" has a molecular weight of 32,400, i.e., it has the 

 formula (C (; H 10 5 ). 20 o- 



Dextrin (C r ,H 10 5 ) 40 (?). By the action of dilute acids in the 

 cold, by the limited action of diastase (the ferment found 

 abundantly in malt, &c.), upon starch paste, or by the action 

 of a temperature of 210 to 280 upon dry starch, dextrin is 

 produced, a substance easily soluble in water and giving no 

 blue with iodine solutions. 



Amylo-dextrin, with the composition C 12 H 2 . 2 O 11 .12C t . ) H 10 5 

 (i.e., consisting of 1 group of maltose and 12 of dextrin), 

 malto-dextrin, C^H^OnAC^R^O^ and other intermediate pro- 

 ducts are formed. They have been examined and described 

 by Brown and Morris, f 



Commercial dextrin or "British gum" is obtained by heat- 

 ing starch to 210 or higher, or by moistening starch with a 

 mixture of nitric and hydrochloric acids and heating it to 100 

 or 125. It is used as a substitute for gum arabic and proba- 

 bly is a complex mixture. 



Dextran or fermentable gum, found in beetroots, is amor- 

 phous, soluble in water, and can be converted into dextrose by 

 boiling with dilute acids. 



Lichenin, found in Iceland moss, is soluble in hot water, but 

 separates in flocks on cooling. 



Glycogen, (C c H 10 O 5 ) n , occurs in the liver and many other 

 parts of the animal. It is a white powder, having a composi- 

 tion (C G H 10 5 ) 2 .H 2 0, and losing its water at 100. It is soluble 

 in water and gives a red colour with iodine. By the action of 

 acids it is converted into dextrose, and diastase converts it 

 into dextrin, maltose, and dextrose. 



Inulin, (C^H . 2 81 ) 2 , occurs in many plants, particularly in 

 tubers of dahlias and Jerusalem artichokes and the roots of 

 dandelion and chicory. It is a white pow^der, soluble in hot 

 but nearly insoluble in cold water or in alcohol. It is not 

 coloured blue by iodine, and by the action of dilute acids is 

 converted into levulose. According to Brown and Morris, J its 



* J.C.S. 1889, Trans. 449. t J.C.S. 1889, Trans. 449. \ J.C.S. 1889, Trans. 464. 



