342 PLANT AND ORGANIC CHEMISTRY 



land moss, and inulin, from many composital plants, act the 

 role of starch in the plants wherein they occur. 



A brief reference may be given here to compounds like 

 dextrin and laevulin, which stand intermediary between the 

 starches and sugars. Dextrin is formed from starch by treat- 

 ing with dilute acids, or by diastase. According to the con- 

 ditions, several dextrin kinds may be separated. A crystal- 

 line form, produced by the action of dilute mineral acids on 

 starch for months, has been isolated. Dextrin gives with 

 iodine a red coloration. 



Glucosides are compounds of grape sugar or glucose with 

 another substance, and naturally find place in a study of car- 

 bohydrates. Grape sugar, on account of its containing an 

 aldehyde group, is capable of uniting with different kinds of 

 chemical bodies to form these compounds. The compound 

 which results on decomposing a glucoside is frequently of a 

 complex nature. Glucosides are very widely spread in nature. 

 In many cases the chemical constitution of glucosides is well 

 known, and some of these compounds have been made syn- 

 thetically. 



Recently, Fischer has described a method of obtaining glu- 

 cosides synthetically. By the action of hydrochloric acid on 

 sugars, alcohols, oxyacids, and phenols, he obtained conden- 

 sation products of the nature of glucosides. These compounds, 

 like other glucosides, do not react with Fehling's solution or 

 with phenyl-hydrazine. But they are decomposed by acids. 1 



1 Also ketones, by warming and treating with hydrochloric acid, are changed 

 into glucosides. Ketones combine with sugar; rhamnose with one molecule; 

 arabinose, fructose, and glucose unite with two molecules of acetone; sarbose, 

 with a ketosane, yields a beautiful crystalline compound. By employing a very 

 weak solution to work with, in contradistinction to the former work with strong 

 hydrochloric acid, o-and )8-stereomers were obtained, also a third product, an 

 acetal compound, analogous to the glucose mercaptans. In the beginning 

 these are in excess, then they go over into glucosides. 



The ketose sugars react with alcohol, in presence of HC1, more quickly than 

 aldosans. 



Fischer has also discovered, as a between-product, glucose-acetone, which 

 is separated in fine, colorless needles. This compound is distinguishable from 

 the glucose di-acetone. 



A new glucoside, similar to amygdalin, but of a simpler formula, named 

 amygdonitril glucoside, has been recently described by Fischer. 



