FIBRINE. 



259 



nises nor dissolves in acetic acid: ammonia acts 

 as potassa, but less energetically. 



When fibrine is digested in solution of per- 

 sulphate of iron, or of copper, or of perchlo- 

 ride of mercury, it combines with those salts, 

 shrinks up, and loses all tendency to putre- 

 faction. When the alkaline solution of fibrine 

 is decomposed by metallic salts, the precipitate 

 consists of the fibrine in combination with the 

 metallic oxide; some of these compounds are 

 soluble in caustic potassa. 



Tannin combines with fibrine, and occasions 

 a precipitate both in its alkaline and acid solu- 

 tions : the tanned fibrine resists putrefaction. 



The ultimate composition of fibrine has been 

 determined by Gay Lussac and Thenard, and 

 by Michaelis, who made a comparative ana- 

 lysis of that of arterial and venous blood : the 

 following are their results: 



Gay Lussac Michaelis. 

 and Thenard. Arterial. Venous. 

 Nitrosen ..19.934... 

 Carbon ..53.360... 

 Hydrogen 7-021... 

 Oxygen . .19.685 23.785 24.065 



.17.587 17.267 



.51.374 50.440 



7.254 8.228 



100.000 100.000 100.000 



The mean of these results gives nearly the fol- 

 lowing atomic composition: 



Atoms. Equivalents. 



Nitrogen 1 14 .... 



Carbon 6 36.... 



Hydrogen 5 5 



Theory. 

 ..19.72 

 ..50.70 

 7.04 



Oxygen 2 16 22.54 



1 71 100.00 



In reference to this atomic estimate, which 

 is suggested by Leopold Gmelin,* Berzelius 

 observes, that from the feeble saturating power 

 of fibrine, its equivalent number is probably 

 very high, that is, that it includes a larger 

 number of simple atoms; but as we have at 

 present no accurate means of determining its 

 combining proportion or saturating power, its 

 atomic constitution cannot be satisfactorily 

 determined. Moreover, it appears that in the 

 above analyses the fat was not separated, nor is 

 any notice taken of the minute portion of sul- 

 phur, the presence of which has been above 

 adverted to. 



When Berzelius first obtained fat from fibrine 

 by digesting it in alcohol and in ether, he con- 

 cluded that it arose from the decomposition of 

 a portion of the fibrine by those agents ; that it 

 was a product and not an educt ; but the sub- 

 sequent experiments of Chevreul leave no 

 doubt that the fat exists ready formed in the 

 blood. This fat is very soluble in alcohol, and 

 the solution is slightly acid ; when it is burned, 

 the ash, instead of being acid, like that of the 

 fatty matter of the brain, is alkaline, whence 

 it appears that it existed saponified, or partly 

 so, in the blood. 



Another important variety of fibrine is that 

 which constitutes muscular fibre, but it is so 

 interwoven with the nerves and vessels and 

 cellular and adipose membrane, that its pro- 

 perties are probably always more or less modi- 



* Handbuch der Theoretischen Chemie. 



fied by foreign matters. The colour of muscles 

 appears to depend upon that of the blood in 

 their capillary vessels; and their moisture is 

 referable to water, which may be expelled by 

 drying them upon a water-bath, when they lose 

 upon an average 75 per cent. If muscular 

 fibre in thin slices is washed with water till 

 all soluble matters are removed, the residue, 

 when carefully dried, does not exceed 17 or 18 

 per cent, of the original weight. 



To obtain the fibrine of a muscle, it must be 

 finely minced and washed in repeated portions 

 of water at 60 or 70, till all colouring and 

 soluble substances are withdrawn, and till the 

 residue is colourless, insipid, and inodorous; 

 it is then strongly pressed between folds of 

 linen, which renders it semitransparent and 

 pulverulent. Berzelius observes that in this 

 state it becomes so strongly electro-positive 

 when triturated, that the particles repel each 

 other and adhere to the mortar, and that it stil 

 retains fat which is separable by alcohol or 

 ether. When long boiled in water, it shrinks, 

 hardens, and yields a portion of gelatine de- 

 rived from the insterstitial cellular membrane; 

 the fibrine itself is also modified by the con- 

 tinued action of boiling water, and loses its 

 solubility in acetic acid, which, when digested 

 with it in its previous state, forms a gelatinous 

 mass soluble in water, but slightly turbid from 

 the presence of fat and a portion of insoluble 

 membrane, derived apparently from the vessels 

 which pervaded the original muscle. It is 

 soluble in diluted caustic potassa, and precipi- 

 tated by excess of muriatic acid, the precipitate 

 being a compound of fibrine with excess of 

 muriatic acid, and which, when washed with 

 distilled water, becomes gelatinous and soluble, 

 being reduced to the state of a neutral muriate 

 of fibrine.* 



When the fibrine of muscle is mixed with 

 its weight of sulphuric acid, it swells and dis- 

 solves, and, when gently heated, a little fat 

 rises to the surface and may be separated : if 

 the mass is then diluted with twice its weight 

 of water and boiled for nine hours, (occasion- 

 ally replacing the loss by evaporation,) am- 

 monia is formed, which combines with the 

 acid, and on saturating it with carbonate of 

 lime, filtering, and evaporating to dryness, a 

 yellow residue remains, consisting of three 

 distinct products : two of these are taken up 

 by digestion in boiling alcohol of the specific 

 gravity of .845, and are obtained upon evapo- 

 ration ; this residue, treated with alcohol of the 

 specific gravity of .830, communicates to it (1) 

 a portion of a peculiar extractive matter, and 

 the insoluble remainder (2) is white, soluble in 

 water and crystallisable, and has been called 

 by Braconnot kucine.\ It fuses at 212, ex- 



* It will be observed, by reference to the article 

 ALBUMEN, that that principle and Jibrine, if not 

 identical, are very closely allied, and appear rather 

 to differ in organization than in essential chemical 

 characters : accordingly the fibrine of the blood may 

 be considered as a modification of seralbumen, and 

 that of muscular fibre as little differing from the 

 fibrine of the blood. 



t Ann. de Chim. et Phys. xiii. 119. 



S 2 



