Miscellanies. 199 



carbon in the blood by the action of the air, or whether venous blood, 

 when it reaches the organs of respiration, contains carbonic acid ready 

 formed, which is merely separated from it. 



M. Magnus passed hydrogen gas through a solution of potash to de- 

 prive the gas of any carbonic acid which it might contain, and when it 

 gave no precipitate with lime water he passed it into the blood of a healthy 

 man ; the gas afterwards made to go through lime water gave a plentiful 

 precipitate of carbonate of lime. Azotic gas similarly employed produced 

 a like effect ; and M. Magnus concludes, from these experiments, that 

 carbonic acid exists ready formed in the blood, and consequently that it 

 is not formed in the lungs. Carbonic acid was also separated from blood 

 by means of the air-pump. 



By using Liebig's apparatus M.Magnus found that blood contained 

 about one fifth of its volume of carbonic acid gas, and when it had been 

 kept twenty four hours, without emitting any bad smell, the quantity was 

 larger. The results were confirmed by employing atmospheric air in- 

 stead of hydrogen gas. 



M. Magnus then ascertained the nature and proportions of all the 

 gaseous contents of the blood. He found that one hundred volumes of 

 the arterial blood of a horse yielded 



Carbonic acid gas, - . - 4.32 vols. 



Oxygen, . - . . ].52 



Azote, - - - - 3. '' 



Total, 7.84 vols. 

 The venous blood of the same horse, drawn four days afterwards, gave 

 Carbonic acid gas, ... 4.29 vols. 



Oxygen, - - - - 1-12 



Azote, .... .,54 " 



Total, 5,95 vols. 



The arterial blood of the calf contains more, and the venous blood 

 less oxygen, than that of the horse. 



M. Magnus observes, that these experiments, and others Avhich we have 

 not copied, appear to show that the gases contained in the blood of the 

 animals, am-ount to about one eighth or one tenth of the quantity era- 

 ployed. He admits however that the experiments are not absolutely pre- 

 cise, because they were not all continued the same length of time, &c. 

 But he observes, that as the proportions between the oxygen and carbonic 

 acid are invariably the same, these results may be regarded as satisfactory. 



With regard to the theory of respiration, all experimentalists agree as 

 to the reciprocal proportions between the carbonic acid expired and of 

 the oxygen absorbed ; while however some of them are of opinion that 

 those quantities are always equal, as must happen if the oxygen gas were 



