( 431 ) 

 SCIENTIFIC INTELLIGENCE. 



PHYSIOLOGY. 



1. On the Gases contained in the Blood, and on Respiration. 

 By M. G. Magnus. — M. Magnus remarks, that it remains a 

 question, whether carbonic acid is formed in the lungs by the 

 oxidisement of a part of the 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. IVIagnus passed hydrogen gas 

 through a solution of potash, to deprive 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 the lime-watei*, 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 24 hours, without emitting any 

 bad smell, the quantity was larger. The results were confirmed 

 by employing atmospheric air instead of hydrogen gas. M. 

 Magnus then ascertained the nature and proportions of all the 

 gaseous contents of the blood. He found that 100 volumes of 

 the arterial blood of a horse yielded carbonic acid gas 4.32 vo- 

 lumes ; oxygen, 1.52 ; azote, 2 ; total 7.84 volumes. The ve- 

 nous blood of the same horse, drawn four days afterwards, gave 

 carbonic acid gas, 4.29 volumes; oxygen, 1.12; azote, 0.54; 

 total, 5.95 volumes. 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 which 

 we have not copied, appear to shew that the gases contained in 

 the blood of the animals amount to about one-eighth or one- 

 tenth of the quantity employed. He admits, however, that the 

 experiments are not absolutely precise, because they were not 

 all continued the same length of time, &c. But be observes, 



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