118 Mr. Thomas Richardson on th6 



1. Fibrin. 



Fibrin, procured as above, has the appearance of soft 

 masses formed of filaments interlaced with each other, 

 which has been conceived by some to be similar to muscular 

 fibre. Its bulk compared with the clot is much smaller, 

 and in this state is heavier than water. To render the 

 fibrin completely pure, according to Berzelius, it ought to 

 be digested in alcohol or ether, to separate a quantity of 

 fatty matters with which it is always united. 



By desiccation, fibrin loses about f of its weight, be- 

 coming a little yellowish, hard, and brittle, on drying. 

 When the fatty matter has been separated, it does not ac- 

 quire any transparency, as was noticed by Berzelius. It 

 has neither taste nor smell. By gently heating fibrin in 

 water it regains its original appearance. By heat it is de- 

 composed, fusing and burning with a brilliant flame, and 

 leaving a shining charcoal behind. When exposed to de- 

 structive distillation it yields water, and the usual products 

 of animal substances. 



The charcoal is consumed with difficulty, caused by the 

 phosphate of lime coating the surface with a glassy matter. 

 The cinder left after burning is of a whitish grey colour and 

 a half liquid consistency ; about f per cent, of the original 

 weight of the dry fibrin according to Berzelius. This 

 chemist found that it leaves traces of silica when dissolved 

 in muriatic acid. Its chief constituent is phosphate of lime. 



The fibrin from the blood of oxen is much more difficult 

 to burn than that from man. This arises probably from 

 the former containing more phosphate of lime than the 

 latter. Before the incineration of the fibrin these sub- 

 stances cannot be obtained by the action of acids ^. 



After coagulation the fibrin is insoluble in cold or hot 

 water. By long continued boiling, however, it changes its 

 appearance and becomes soft. During the boiling it 

 evolves no gas, but the solution becomes milky. Evapo- 

 rating the solution to dryness, there remains a solid mass 

 behind, brittle, of a slight yellow colour, and possessed of 

 an agreeable flavour of boiled meat. It is soluble in 

 water, but the solution is not similar to that of gelatine ; it 



* Berzelius' Chimie, vii., 35. 



