360 LIQUID PARTS OF ANIMALS. 



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

 larly changed every day. The fibrous part was now pressed and 

 dried by the heat of a water bath. In this state it possessed 

 the characters of almost pure fibrin.* 



It is extremely difficult to free the fibrin of blood completely 

 from the 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 well-washed in cold water till that liquid ceas- 

 es to be coloured. Then steep it in cold 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 se- 

 parate a fatty matter which it still contains. 



3. Hematosin. This name was given by M. Chevreul to the co- 

 louring matter of blood, which Dr Wells, as early as 1797, show- 

 ed to be an animal substance of a peculiar nature. Vauquelin 

 and Brande proposed processes for obtaining it in an isolated 

 state. But they did not succeed in freeing it from the albumen 

 with which it is always mixed in the crassamentum. The pro- 

 cesses of Berzelius and Engelhart enabled chemists to obtain 

 hematosin in a state of tolerable purity ; but, as it was coagulat- 

 ed and consequently insoluble in water, it was not possible to de- 

 termine its characters with the requisite precision. 



4. Cholesterin. This is the name by which the white crys- 

 talline matter constituting the principal part of human biliary 

 calculi has been distinguished. Its existence in the serum of 

 blood was discovered in 1833, by M. Felix Boudetf His dis- 

 covery was confirmed by Lecanu in 18374 It was extracted in 

 the following manner : 1000 grammes of human serum were 

 dried over the vapour bath, the dry residue was pulverized, passed 

 through a sieve, and treated three times with ether in Chevreul's 

 digester. The etherial liquids were mixed together, and three- 

 fourths of them were distilled off. The residue was evaporated 

 to dryness over the vapour bath. A considerable quantity of 

 matter remained, which had a fatty aspect, a disagreeable smell, 

 and the consistence of honey. 



When digested in alcohol a portion was dissolved, which had 

 a yellow colour and reacted as an acid, When left to spontane- 

 ous evaporation it deposited a pearly matter, which possessed the 

 characters of cholesterin. 



* Phil. Trans. 1800, p. 327. f Jour, de Pharm. xix. 294. 



| Etudes Chimiques sur le Sang Humain, p. 46. 



