354 PROTEIN-COMPOUNDS. 



therefore regards it as a higher stage of oxidation of his hypo- 

 thetical protein, combined with sulphamide and phosphamide, and 

 assigns to it the hypothetical formula, (C 36 H 25 N 4 O n .2HO) + 

 H 2 NS + H 2 NP. Fats are always associated with fibrin; and 

 although they have not been thoroughly investigated, they would 

 appear to consist principally of soaps of ammonia and lime. (Berze- 

 lius*, Virchowf.) Dry fibrin contains about 2.6% of these fats. 



Like all protein-compounds, fibrin contains mineral substances, 

 of which the principal is phosphate of lime. Mulder found 

 1'7, but Virchow only Q'66% of this salt mixed with a little 

 carbonate of lime. 



Compounds. Fibrin-protein, binoxide of protein, correspond- 

 ing, according to Mulder's hypothesis, to the formula 

 6(C 36 H 25 N 4 O 11 .2HO)+S 2 O 2 , occurs, as we learn from the 

 same observer,;]: in most animal fluids, associated in larger or 

 smaller quantity with fibrin. It may be obtained from boiled 

 fibrin or vitellin, precisely in the same manner as albumen- 

 protein from albumen, or by boiling the fibrin for a long time in 

 water exposed to the air, or lastly by treating hair or horn with a 

 solution of potash, filtering the boiled fluid, and precipitating 

 with acetic or hydrochloric acid. It may be purified by repeat- 

 edly dissolving it in caustic potash, and precipitating it with acetic 

 acid. 



This body forms a light yellow, lumpy, tough precipitate, 

 which, when dried in the air, cakes together into a blackish green, 

 shining, resinous mass, and on trituration, forms a dark yellow 

 powder ; it becomes very viscid in warm water, and admits of 

 being drawn into long, silky, shining bands and threads ; it renders 

 water in which it is boiled only slightly turbid, and is perfectly 

 insoluble in alcohol and ether ; in dissolves in dilute acetic acid 

 and in dilute mineral acids ; nitric acid does not communicate to 

 it so well marked a yellow colour as to the other albuminous 

 substances ; when dissolved in acids it may be precipitated by 

 yellow and red prussiate of potash, by tannic acid, and by ace- 

 tate of lead ; it is readily soluble in alkalies, from which it may 

 again be precipitated by acids, it fuses on being heated, and finally 

 carbonises, with the evolution of a horn-like odour. 



Preparation. The method first adopted by Joh. Miiller is 

 generally employed for obtaining the natural solution of the fibrin- 



* Lehrb. d. Chem. Bd. 9, S. 88. 



t Zeitschr. f. rat. Med. Bd. 4, S. 269 ff. 



t Untersucb. libers.' v. Volcker. H. 2, S. 253. 



