FIBRINE, (Fr.fibrine; Germ. Faserstojr) Under this name physiologists and chemists have generally described the animal proximate principle constituting that part of muscular fibre which is insoluble in cold water, and that portion of the coagulum of blood which re mains after the removal of its colouring matter.
The fibrine of blood is best obtained by stirring a quantity of fresh-drawn blood with a piece of wood, to which the coagulum adheres, and may afterwards be washed in large and repeated portions of water till it loses its co louring particles, and remains in the form of a buff-coloured, fibrous, and somewhat elastic substance ; this may then be partially dried by pressure between folds of blotting-paper, di gested in alcohol to remove fat, and then care fully dried, during which process it loses about three-fourths of its weight, and becomes brittle and of a yellowish colour: it is insipid and in odorous. In cold water it slowly resumes its original appearance but does not dissolve: when, however, it is subjected to the long continued action of boiling water it shrinks and becomes friable, and a portion of a newly formed substance is at the same time taken up by the water, which gives it a yellowish colour and the smell and taste of boiled meat, and winch, 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 allibrine. 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.
Alariatic acid gelatinises fibrine and then gradually dissolves it, forming a dark blue liquid, or purple and violet, if retaining any hrematosin. This solution, when diluted with water, deposits a white muriate fibrin,, 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 mnriatic solu tion. When boiled in the acid, nitrogen is evolved, and a solution is obtained, which, after the 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.