242 ALBUMINOIDS. 



tion, and applying a fe^v qualitative tests to shoM' the presence of 

 one or more of the substances referred to. 



§235. Properties: Glutenfihr'in. — Glutenfibrin is insoluble in 

 water and in absolute alcohol, but dissolves easily in warm 30 to 

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

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

 water converts it into a gelatinous substance insoluble in spirit, 

 acids, or alkalies. Glutenfibrin 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 neutralizing, 

 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, but, like glutenfibrin, it undergoes simultaneoiisly 

 a partial decomposition. Gliadin is insoluble in absolute 

 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 with con- 

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

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

 Attention has already been directed (§ 224) to the 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 precijiitated from 

 a cold solution by 90 to 95 per cent, spirit in flochs or friable 

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

 it yields a cloudy mucilaginous liquid, Avhich clears again on 

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

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

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



^ On concentrating 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. 



- Glutenfibrin agrees with maize-fibrin 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, citric, tartaric and oxalic acids. 

 Zander has recently reported on another albuminous substance soluble in 

 spirit ('Chemisches über die Samen des Xanthium Strumarium.' Diss. 

 Dorpat, 1881). 



