220 THE CARBOHYDRATES. 



treated with alkali, with a hydrochloric-acid solution of dimethylaminobenzalde- 

 hyde, when a beautiful red color is obtained. 



Glucosamine is best prepared from decalcified lobster-shells by treat- 

 ing with hot concentrated hydrochloric acid. 1 In regard to its prepara- 

 tion from protein substances we must refer to the works cited on page 

 84, footnote 5. 



Albamine (diglucosamine), (CeHnCXN^+HaO, is the name given by S. FRAN- 

 KEL 2 to a body which he isolated from the products of the hydrolysis of ovalbumin 

 with baryta, as well as in its digestion. Albamine is amorphous, dextrogyrate, 

 and reduces after boiling with acids. As hydrolytic cleavage product it yields 

 d-glucosamine. 



Galactosamine is claimed to have been found by SCHULZ and DITTHORN in 

 a glycoprotein of the spawn of the frog. This claim is not generally accepted. 

 v. EKENSTEIN and BLANKSMA 3 obtained galactose on the hydrolysis of the slimy 

 envelope of frog eggs. 



According to OFFER, 4 pentosamine occurs in the liver of the horse. Accord- 

 ing to OFFER, the pentose derivative, which he calls dipentosamine (C 5 H 7 03.NH 2 )2+ 

 H 2 and a second, perhaps a diacetyl-pentosamine 2(CH 3 CO)CioHi 8 N 2 07 (?), 

 also occur in the liver. The first gives pentose reactions and reduces FEHLING'S 

 solution after boiling with acid. The only amino-sugar positively detected in 

 the annual organs is glucosamine. 



The amino-sugars, as intermediary bodies between the carbohydrates 

 and oxyamino-acids, are of great physiological interest, and this interest 

 has become still more important since NEUBERG was first able to pre- 

 pare the corresponding amino-aldehyde from glycocoll and then also 

 from other amino-acids. From the ethyl ester of glycocoll in acid solu- 

 tion NEUBERG 5 obtained the amino-acetaldehyde. NH2.CH2.CHO, by 

 treatment with sodium amalgam. This aldehyde is very unstable and 

 has a tendency to condensation with ring formation, and NEUBERG 

 obtained therefrom by oxidation with corrosive sublimate and caustic 

 soda, pyrazine according to the equation: 



.LI 



i 



NH 2 



N 

 H 2 +CHO ^\ 



| HC CH 



CHO CH 2 +0= || +3H 2 



| HC CH 



NH 2 V/ 



N 



1 See Hoppe-Seyler-Thierfelder's Handbuch, 8. Aufl. 



2 Monatsh. f. Chem., 19. 



3 Schulz and Ditthorn, Zeitschr. f. physiol. Chem., 29; v. Ekeastein and Blanksma, 

 Chem. Centralbl., 1907, 2, p. 1001. 



4 Hofmeister's Beitrage, 8. 



6 Ber. d. d. chem. Gesellsch., 41. 



