258 



FIBRINE. 



which, when obtained by evaporation, is brittle, 

 yellow, and again soluble in water: this solu- 

 tion is rendered turbid by infusion of galls, 

 but the precipitate differs from that yielded by 

 gelatin, and appears to be a distinct product. 

 The insoluble residue has lost its original cha- 

 racters; it no longer gelatinises with acids or 

 alkalies, and is insoluble in acetic acid and in 

 caustic ammonia. 



The action of acids and alkalies upon the 

 fibrine of blood has been studied in detail by 

 Berzelius and others ; the following is an ab- 

 stract of their results.* 



All the acids, except the nitric, render fibrine 

 transparent and gelatinous : the diluted acids 

 cause it to shrink up. In sulphuric acid it 

 acquires the appearance of a bulky yellow jelly, 

 which immediately shrinks upon the addition 

 of water, and is a combination of the acid and 

 fibrine ; when well washed upon a filter it gra- 

 dually becomes transparent and soluble, and 

 in that state is a neutral sulphate of fibrine. It 

 is again rendered opaque by dilute sulphuric 

 acid, and is precipitated from its aqueous solu- 

 tion by that acid in the form of white flakes, 

 which appear to be a supersulphate. When 

 fibrine is heated in sulphuric acid, both are 

 decomposed, the mass blackens, and sulphu- 

 rous acid is evolved. If the colouring matter 

 has not been entirely washed out of the fibrine, 

 the sulphuric solution is of a brown or purple 

 colour. 



Nitric acid communicates a yellow colour to 

 fibrine, and, if cold and dilute, combines with 

 it to form a neutral nitrate, analogous to the 

 sulphate When fibrine is digested in nitric 

 acid, nitrogen is evolved, and its composition 

 considerably changed, as we shall more parti- 

 cularly mention in describing the action of this 

 acid on muscular fibre. 



Muriatic acid gelatinises fibrine and then 

 gradually dissolves it, forming a dark blue 

 liquid, or purple and violet, if retaining any 

 haematosin. This solution, when diluted with 

 water, deposits a white muriate of fibrine, 

 which, like the sulphate, gelatinises when the 

 excess of acid is washed away, and becomes 

 soluble, and is again thrown down from its 

 aqueous solution by excess of acid. The blue 

 liquid, after the separation of the precipitate by 

 dilution, retains its colour, but loses it when 

 saturated with ammonia, and with excess of 

 ammonia becomes yellow. Fibrine digested 

 in dilute muriatic acid is converted into the 

 same white compound as that precipitated 

 by water from the concentrated muriatic solu- 

 tion. W r hen boiled in the acid, nitrogen is 

 evolved, and a solution is obtained, which, after 

 4he saturation of the acid, is precipitated by 

 infusion of galls, but not by alkali or ferrocy- 

 anuret of potassium ; on evaporating the solution 

 to dryness a dark brown saline mass remains, 

 so that the fibrine appears to have undergone 

 some decomposition. 



* Berzelius, Lehrbuch der Thier-Chemie, Wbh- 

 ler's German translation. Dresden, 1831. See 

 also Medico-Chirurgical Transactions, vol. iii. 

 p. 201. 



A solution of recently-fused phosphoric acid 

 acts upon fibrine in the same way as the sul- 

 phuric acid ; but if the acid solution has been 

 kept for some weeks, the fibrine then forms 

 with it a soluble jelly, which is not precipitated 

 by excess of acid. 



Concentrated acetic acid converts fibrine into 

 a jelly easily soluble in warm water. When 

 this solution is boiled, a little nitrogen is evolved, 

 but nothing is precipitated ; when gently eva- 

 porated, it gelatinises, and leaves, on desic- 

 cation, an opaque insoluble residue. The other 

 acids added to this acetic solution produce 

 precipitates which are compounds of fibrine 

 with the added acid. Fibrine is also preci- 

 pitated from the acetic solution by caustic pot- 

 assa, but is redissolved by excess of alkali. 



The acetic solution of fibrine is precipitated 

 in white flakes by ferrocyanuret of potassium : 

 this precipitate, when dried, appears to be a 

 compound of fibrine with cyanuret of iron 

 and hydrocyanic acid ; it is insoluble in dilute 

 acids, but is decomposed by caustic alkalis, 

 which abstract the cyanuret of iron and hydro- 

 cyanic acid, and the remaining fibrine first 

 gelatinises and then dissolves. 100 parts of 

 this compound, carefully dried at 167, and 

 then incinerated in a weighed platinum cru- 

 cible, gave 2.8 red oxide of iron,=7.8 of the 

 combination of cyanuret of iron with hydro- 

 cyanic acid; whence it follows that 92.2 of 

 fibrine were contained in the white precipitated 

 compound. 



Caustic potassa, even much diluted, dissolves 

 fibrine. If the solution is very dilute, the 

 fibrine gradually forms a bulky jelly, which, 

 heated in a close vessel to about 130, dissolves 

 into a pale yellow liquid, not quite transparent, 

 and which soon clogs a filter. The yellow tint 

 appears to arise from the presence of a small 

 portion of adhering haematosin. When this 

 alkaline solution is saturated by muriatic or 

 acetic acid, it exhales a peculiar fetid odour and 

 blackens silver, announcing the presence of 

 sulphur, so that the animal matter seems to 

 have suffered some slight change. It is stated 

 by Berzelius that fibrine is capable of neutral- 

 izing the alkali, and that such neutral com- 

 pound may be obtained by dissolving the 

 fibrine in the alkaline solution, and adding 

 acetic acid till it begins to occasion a precipi- 

 tate ; the filtered liquid is then perfectly neu- 

 tral, but the potassa bears a very small propor- 

 tion to the fibrine. This neutral solution, he 

 says, much resembles white of egg, and is, 

 coagulated by alcohol and acids, though not by 

 heat. Gently evaporated, it gelatinises, and, 

 when dry, assumes the appearance of albumen 

 dried without coagulation. In this state it 

 dissolves in warm water, and is first thrown 

 down, and then redissolved by the acids when 

 added in excess. Alcohol throws down nearly 

 the whole of the fibrine from its neutral alkaline 

 solution : if there be excess of alkali, much of 

 the fibrine is retained. Mr. Hatchett found that 

 fibrine, when digested in strong caustic potassa, 

 evolved ammonia and yielded a species of soap; 

 acids occasion a precipitate in this solution 

 which is altered fibrine, for it neither gelati- 



