121 



with atmospheric air. A quantity of this fluid was 

 received into a cup, and confined in a jar of air in- 

 verted in water, a glass of lime-water having been 

 previously placed in the cup. The internal surface 

 of the jar was soon bedewed with moisture, and a 

 pellicle began to form on the lime-water, which in 

 a few hours was increased to a thick crust of carbo- 

 nate of lime. The crassamentum was then removed, 

 and a fresh glass of lime-water was placed in the se- 

 rum, which in thirty-six hours had acquired a crust 

 like the former, and the water had risen considera- 

 bly into the jar. In another experiment, where the 

 serum was placed for twenty-four hours in a jar of 

 air inverted in mercury, the residual air rendered 

 lime-water milky, and the remainder had lost a part 

 of its oxygen. A similar production of carbonic 

 acid seems to have occurred, when, with a small di- 

 minution of the gas, a slight change of colour was 

 produced on venal blood by placing it in contact 

 with nitrous oxide, in the experiments of Mr Davy : 

 for when a solution of strontian was admitted to the 

 oxide, it became slightly clouded, and, with the di- 

 minution of bulk that followed, minute portions of 

 carbonic acid and nitrogen gas were produced *. 

 Hence then we learn, that when venal blood is ex- 

 posed to the contact of atmospheric air, of oxygen 

 gas, or of nitrous oxide, it presently assumes a florid 

 colour, and, at the same time, the volume of air is 

 somewhat diminished, and a portion of carbonic 

 acid is produced. 



Researches, p. V ST7, 380, 387. 



