FIBRIN FROM BLOOD. 193 



globules consist of three distinct substances, namely, hematosin, 

 albumen, and fibrin.* 



Fibrin may be procured likewise from the muscles of animals. 

 Mr Hatchett cut a quantity of lean beef into small pieces, and 

 macerated it in water for fifteen days, changing the water every 

 day, and subjecting the beef to pressure at the same time, in or- 

 der to squeeze out the water. The shreds of muscle, which 

 amounted to about three pounds, were now boiled for five hours every 

 day for three weeks in six quarts of fresh water, which was re- 

 gularly changed every day. The fibrous part was now subject- 

 .ed to pressure, and then dried on the water-bath. In this state, 

 it possessed the characters of fibrin.f 



It is very difficult to free the fibrin of blood completely from 

 hematosin. The easiest way is to stir new-drawn ox-blood 

 rapidly with a stick. The fibrin adheres to the stick. Let it be 

 taken off, and washed in cold water till that liquid ceases to be 

 coloured by it. Then steep it in water for twenty-four hours, 

 washing it frequently and carefully during that time, Finally, 

 let it be digested in alcohol, or still better in ether, to separate 

 a fatty matter which it still contains. 



Fibrin, when dried, assumes a dirty-yellow colour, and be- 

 comes hard and brittle, but continues opaque. When put into 

 water, it imbibes that liquid, and recovers its original appear- 

 ance, and nearly its original weight. It has neither taste nor 

 smell. When heated, it does not alter till it reaches the point 

 of decomposition. It then melts, swells greatly, catches re, 

 and burns with a yellow flame, giving out much smoke. It is 

 insoluble in water, whether cold or hot. When boiled in that 

 liquid, it contracts and becomes at last extremely friable. The 

 water becomes muddy, and if we evaporate it to dry ness, we ob- 

 tain a solid, brittle, yellow substance, having the smell of boiled 

 meat, and soluble in water. This substance does not assume the 

 form of a jelly, and is precipitated by tannin in insulated flocks, 

 which do not unite into an elastic mass like tannate of gelatin. 



Fibrin, like albumen and casein, possesses both the characters 

 of an acid and a base. The concentrated acids cause it to swell, 

 and to become gelatinous and transparent. With sulphuric acid, 

 it swells into a yellow jelly, but. does not dissolve. Heat is evolv- 



* Lecanu, Etudes Chimiques sur le Sang Humain, p. 5. 

 f Phil. Trans. 1800, p. 827. 



