134 CIRCULATING FLUIDS : 



failed in observing any development of carbonic acid under tlie 

 air-pump. 



Hoffmann and Stevens could not obtain carbonic acid either 

 by the application of heat or by the air-pump ; but they ob- 

 served that if freshly-drawn blood be shaken with hydrogen^ 

 carbonic acid is then evolved. Another experiment in favoiu* 

 of the existence of carbonic acid in the blood has been insti- 

 tuted by Miiller. Nysten and CoUard de Martigny made 

 animals inhale gases entirely devoid of oxygen, and observed 

 the formation of carbonic acid. Miiller and Bergemann made 

 frogs breathe pure hydrogen and nitrogen, and observed that, 

 after the animals had remained in these gases from 6 to 22 

 hours, they had expired a quantity of carbonic acid, varying 

 from 0-25 to 0-83 of a cubic inch. 



Magnus has published a series of accurate experiments which 

 must be regarded as quite decisive respecting the amount of 

 carbonic acid and oxveen in arterial and venous blood. He 

 passed a current of hydrogen through recently drawn blood, 

 and found that carbonic acid was given off in a constantly de- 

 creasing ratio. He likewise analysed the whole of the gas that 

 he obtained from the blood, and found its composition as 

 follows : 



Volumes in cubic centimeters. Gas. r 5*4 COo 



Blood of a horse .... 125 . yielded 9-8 -^ 1-90 



I 2-5 N 

 r 8-8 CO2 



Venous blood of a horse . . 205 . . . 12-2 < 2-3 O 



L 1-1 N 

 rlO-0 CO., 



Ditto 195 .. , 14-2 J 2-5 



L 1-7 N 

 plO-7 CO2 



Arterial blood of a horse . . 130 . . . 16-3 J 4-10 



1 1-3 N 

 r 7-0 CO2 



Ditto 122 .. . 10-2 J 2-2 



I 1-0 N 

 rl2-4 CO2 



Venous blood of the same horse . 170 . . . 18-9 J 2-5 



L 4-0 N 



Arterial blood of the calf . , 123 



9-4 CO., 



{y4 v 

 3-5 

 1-6 N 



