QUANTITY OF BLOOD. 113 



Elementary Composition of dried Ox Blood. 



Carbon 519.50 



Hydrogen 71.70 



Nitrogen 150.70 



Oxygen 213.90 



Ashes 44.20 



1000.00 



This table leads to the hypothetical formula of the ultimate constitu- 

 tion of blood: ' 



^48 H 39 ^6 15 



As to the quantity of blood in the circulation, it has been variously es- 

 timated. It may perhaps be taken at one eighth of the weight Q uantit of 

 of the body, a number which is agreed upon by several authors, blood in the 

 and in support of which Lehmann mentions the following in- y " 

 teresting observation: "My friend, E. Weber, determined, with my co- 

 operation, the weights of two criminals before and after decapitation. The 

 quantity of blood which escaped from the body was determined in the 

 following manner : Water was injected into the vessels of the trunk and 

 head until the fluid escaping from the veins had only a pale red or yel- 

 low color. The quantity of blood remaining in the body was then calcu- 

 lated by instituting a comparison between the solid residue of this pale red 

 aqueous fluid and that of the blood which first escaped. By way of illus- 

 tration, I subjoin the results yielded by one of the experiments. The living 

 body of one of the criminals weighed 60, 140 grammes ; and the same body, 

 after the decapitation, 54,600 grammes; consequently, 5540 grammes of 

 blood had escaped. 28.560 grammes of this blood yielded 5.36 grammes 

 of solid residue ; 60.5 grammes of sanguineous water collected after the 

 injection contained 3.724 grammes of solid substances. 6050 grammes 

 of the sanguineous water that returned from the veins were collected, and 

 these contained 37.24 grammes of solid residue, which corresponds to 

 1980 grammes of blood; consequently, the body contained 7520 grammes 

 of blood (5540 escaping in the act of decapitation, and 1980 remaining in 

 the body) ; hence the weight of the whole blood was to that of the body 

 nearly in the ratio of one to eight. The other experiment yielded a pre- 

 cisely similar result." 



A short time after it has been drawn, the blood undergoes coagulation, 

 and is then said to be composed of the serum and the clot. Spontaneous 

 In this state it is sometimes spoken of as dead. The plasma seramand t0 

 of living blood differs from the serum of dead in containing clot, 

 fibrin. 



The coagulation of the blood commences within about ten minutes 

 after it has been drawn, and the clot undergoes a subsequent The coaguia- 

 condensation during one or two days. To understand the tlon of blood - 

 physical nature of this singular change, we may conveniently regard the 



H 



