242 ALBUMINOIDS. 



tion, and applying a fe^v- qualitative tests to show the presence of 

 one or more of tjie substances referred to. 



§2-35, Frffperim: Glutenfibrin. — Glutenfibrin is insoluble in 

 water and in a.bsolute alcohol, but dissolves easily in warm 30 to 

 70 per cent, spirit, separating again on cooling.^ It is also taken 

 up fay cold 80 to 90 per cent, spirit. Prolonged boiling with 

 water converts it into a gelatiiious substance insoluble in spirit, 

 acids, or alkalies. G-lutenfibria dissolves with facility, in cold 

 dilute acids (acetic, citric, tartaric, hydrochloric), and in alkalies ; 

 with ammonia, lime- and baryta- water it gelatinizes. It is pre- 

 cipitated from both acid and alkaline solutions on neutrab'zing, 

 and is also thrown down by acetate of copper. ^ 



Gliadin is characterized by its tough, .slimy consistency. It is 

 sparingly soluble in cold water ; a considerable quantity dissolves 

 on boiling, hut, like glutenfibrin, it undergoes simultaneously 

 a partial decomposition. Gliadin is insoluble in absohite 

 alcohol, but dissolves in 60 to 70 per cent, spirit, both cold and 

 warm (especially freely in the latter). In general it resembles 

 glutencasein in its behaviour to dilute alkalies and acids, but 

 ammonia, lime- and baryta- water dissolve it. Boiled v^ith con- 

 centrated hydrochloric acid it yields a bluish-brown solution. It 

 is precipitated by acetate of copper, but not by mercuric chloride. 

 A-ttention has already been directed (§ 224) to this high percentage 

 of nitrogen in gliadin. 



Mucedin is far less tough and elastic than gliadin, and is more 

 easily soluble in 60 to 70 per cent, spirit. It is precipitated from 

 a cold solution by 90 to 9-5 per cent, spirit in flocks or friahle 

 inasses (solutions of gliadin become milky) ; stirred up with water 

 it yields a cloudy mucilaginous liquid, which clears again on 

 standing ; but, if wanned, the aqueous solution becomes cloudy 

 and remains so for a considerable period, tiU finally a flocky mass 

 separates which is only partially soluble in acetic acid and spirit. 



■ On cancentrafcing such solutions the glutenfibrin forms a skin on the sur- 

 face of the liquids, which dissolves again on stirring. Gliadin and mucedin 

 do not exhibit this peculiarity.' 



^ Griutenfibrin agrees with maize-fihriu in most of its properties ; the latter 

 contains only 15-5 (instead of 16-9) per cent, of nitrogen, and is insoluble, or 

 only partially dissolved, by dilute acetic, citrip, tartaric and oxalic acids. 

 Zander has recently reported on another albuminous substance soluble in 

 spirit ('Chemisohes Uber die Sainen des Xanthium Strumarium.' Diss. 

 Dorpat, 1881). 



