116 Mr, Thomas Richardson on the 



Article VI. 



Of the Chemical Composition of Human Blood, By Mr. 

 Thomas Richardson. 



The apparent solidity of the whole of the hlood after coa- 

 gulation is only a deception, for as the truly solid portion, 

 which is called the clot, contracts, a liquid, termed serum, 

 is forced out upon the surface, and if it be allowed to stand 

 fora few hours, this greenish yellow fluid may be drawn off. 

 The proportion between the clot and serum varies very 

 much in different animals, and even in the same animal 

 in different circumstances. Dr. Thomson states, that the 

 following may be taken as the mean in healthy human 

 blood. 



Serum .... 55 



Clot 45 



Dumas and Prevost, after numerous experiments upon 

 this subject, find in the following instances 



Man. Horse. Tortoise. Chicken. Trout. 



Water . 7839 8183 7688 7970 8637 

 Particles 1242 920 1506 1466 638 



Serum . 869 897 806 564 725 



These gentlemen have also found more particles in the 

 arterial than in the venous blood. In a comparative ana- 

 lysis of the arterial and venous blood of a sheep they ob- 

 tained as follows : 



Arterial. Venous. 



Water .... 8293 8364 

 Particles . . . 935 861 



Albumen and salts 772 775t 



Muller has confirmed these results ; since it appears 

 from his experiments, that the arterial blood of the goat 

 contained 0*483 and venous blood -395 percent, of dissolved 

 fibrin. % 



Lucanu, from several experiments upon the blood of in- 

 dividuals of different sexes, age, and temperament, draws 



• Phil. Mag. xi., p. 349. f Ann. de Ch. et Ph. xrii., p. 64. 

 X Pogg. Annalen, xxx., 313., and Records ii. 16. 



