198 THE CARBOHYDRATES. 



esters, and perhaps the chondroitin sulphuric acid and the glucothionic 

 acid are sulphuric acid esters. The nature of these two groups of 

 sulphuric acid esters is not yet thoroughly understood. 



The sugars can also combine with other bodies and with each other, 

 forming ether-like combinations. By the action of hydrochloric acid 

 as catalyst, as shown by FISCHER and collaborators, the sugars split oft 

 ~water and unite with other bodies, producing lactone-like combinations, 

 Tvhich have been called glucosides. These glucosides, which are generally 

 compounds with aromatic groups, occur widely distributed in the vegeta- 

 ble kingdom. The more complex carbohydrates may be considered, 

 according to FISCHER, as glucosides of the sugars. Thus maltose, for 

 example, is the glucoside and lactose the galactoside of dextrose. The 

 glucosides can be split into their components by chemical agents, boiling 

 with dilute mineral acids, as well as by the action of enzymes. The com- 

 plex sugars hereby yield simple sugars and the other glucosides yield 

 compounds which belong either to the aromatic or the aliphatic series 

 "besides the sugar. A long-known example of a decomposition of this kind 

 is the splitting of amygdalin by the enzyme emulsin. It yields glucose, 

 benzaldehyde and hydrocyanic acid according to the equation: 



CaoHsrNOj l + 2H 2 O = 2C 6 Hi 2 O 6 + C 6 H 5 COH + CNH. 



With phenylhydrazine or substituted phenylhydraziries, the sugars 

 first yield hydrazones with the elimination of water, and then on the further 

 action of hydrazine on warming in an acetic -acid solution we obtain 

 osazones. 



The reaction takes place with the aldoses as follows: 



(a) CH 2 (OH).[CH(OH)] 3 .CH(OH).CHO + H 2 N.NH.C 6 H 5 = 



CH 2 (OH).[CH(OH)] 3 .CH(OH)CH:N.NH.C 6 H 5 + H 2 0. 



Phenylglucosehydrazone 



(6) CH 2 (OH) [CH (OH)] 3 .CH (OH) .CH : N.NH.C 6 H 5 + H 2 N.NH.C 6 H 5 = 



CH 2 (OH).[CH(OH)] 3 .C.CH:N.NH.C 6 H 5 ] 



N.NH.C 6 H 5 + H 2 O + H 2 . 



Phenylglucosazone 



and with the ketoses: 



CH 2 (OH)[CH(OH)] 3 CO.CH 2 (OH)+H 2 N.NH.C 6 H 5 = 



CH 2 (OH)[CH(OH)] 3 C.CH 2 OH 



N.NH.C 6 H 5 + H 2 O, 

 and CH 2 (OH)[CH(OH)] 3 .C.CH 3 (OH) 



N.NH.C 6 H 5 +H 2 N.NH.C 6 H 5 = 



CH 2 (OH) [CH(OH)] 3 .C.CH : N.NH.C 6 H 5 + H 2 O + H 2 . 



N.NH.C 6 H 5 



The hydrogen is not evolved, but acts on a second molecule of phenylhy- 

 tdrazine and splits it into aniline and ammonia : 



H 2 N.H.C 6 H 5 + H 2 = H 2 N.C 6 H 5 + NH 3 . 



