•380 Proceedings of the Royal Irish Academy, 



The substances oMained in this "^ay were very hygroscopic and 

 decomposed even by solution in water. 



The most convenient and fruitful method for the synthesis of 

 glycosides was discovered by Emil Fischer.^ In the first instance, he 

 condensed the sugar with an alcohol or mercaptan, in presence of a 

 large excess of cold, strong hydi-ochloric acid. The later and more 

 convenient method consisted in heating the sugar and alcohol with a 

 small quantity of hydrochloric acid. 



In this way Pischer and his pupils obtained the glucosides of 

 methyl, ethyl, propyl, and benzyl alcohols, of glycol and of glycerine, 

 of dimethyl acetal, of ethyl, amyl, benzyl, ethylene, and trimethylene 

 mercaptans ; the galactosides of methyl and ethyl alcohols, of ethyl, 

 benzyl, and ethylene mercaptans ; the mannosides of methyl alcohol, 

 of ethyl, and ethylene mercaptans ; the fi'uctoside of methyl alcohol ; 

 the glucoheptosides of methyl alcohol and ethyl mercaptan; the 

 rhamnosides of methyl and ethyl alcohols, of ethyl, benzyl and 

 ethylene mercaptans ; the arabinosides of methyl, ethyl, and benzyl 

 alcohols, of ethyl, benzyl, and trimethylene mercaptans ; the xylosides 

 of methyl alcohol and the sorboside of methyl alcohol. 



Although the glycosides of the monatomic phenols cannot be 

 obtained by Fischer's method,- those derived from the polyatomic 

 phenols resorcine, pjrocatechine, pyi'Ogallol, and phlorogluciae with 

 arabinose have been so obtained. In a similar manner the glucosides 

 of resorcine, orcine, and phloroglucine with the galactoside, fi'uctoside, 

 and mannoside of phloroglucine were synthesised.^ 



Another method for synthesising glycosides was discovered by 

 Hill,* who found that zymohydrolysis is a reversible operation. He 

 obtained maltose from glucose by the action of maltase ; but later 

 experiments by Emmeiiing^ seem to show that the disaccharide 

 obtained by HiU's method was isomaltose. Similarly by the action 

 of the kephyr lactase on a mixture of galactose and glucose, Emil 

 Fischer and Armstrong*' obtained galactosido-glucose (isolactose). 



The discovery of a method of obtaining a crystalHne mother sub- 



1 Berichte, xxvi. (1893), pp. 2400, 2928 ; xxvii. (1894), pp. 674, 2483, 2985 ; 

 xxviii. (1895), p. 1145. 



- Emil Fischer and Jennings, Bericlite, xxvii., 1894, p. 1358. 



^ Bericlite, xxviii., 1895, p. 24. 



^ Journ. Chem. Soc, Ixxiii., 1898, p. 634. 



* Berichte, xxxiv., 1901, p. 600. 



« Sitz. der K. Akad. der Wissensch., Berlin, 1901, xii., p. 123. 



