A HISTORY OF METABOLISM 33 



volume of carbonic acid equal to their own volume and larger in quantity 

 than they would have expired had they breathed in air. He concluded 

 that carbon dioxid was not formed by oxidation in the lungs but must 

 have been excreted from the blood, and he supports this conclusion by 

 citing unpublished experiments by Vauquelin in which blood was exposed 

 to a hvdrogen atmosphere with the result that carbonic acid was given 

 off. 



Magnus (1802-1870) repeated the experiments of Vauquelin, shaking 

 blood in hydrogen gas, and he also placed blood in a complete vacuum 

 and 'noticed the elimination of a great volume of gases. There was more 

 carbonic acid eliminated than could be accounted for by the bicarbonate 

 present. 



Gay-Lussac (1778-1850) criticized these results .and stated that the 

 quantity of oxygen found in the blood was sixteen times larger than could 

 be dissolved by water and that no differences appeared in the analyses of 

 arterial and venous bloods. Magnus (1845) replied that 100 parts of gas 

 extracted from blood contained : 



Arterial Blood Venous Blood 



Carbonic acid 62.3 71.6 



Oxygen 23.2 15.3 



Nitrogen 14.5 13.1 



100 100 



He found also that when blood was pumped out it could again absorb 

 sixteen volumes per cent of oxygen. 



Berzelius (1779-1848) announced in 1838 that little oxygen could be 

 added to blood serum freed from corpuscles, but when the serum was mixed 

 with the coloring matter of the blood it was absorbed in large volume. 

 Berzelius attributed the affinity of "hematin" for oxygen to its content 

 of iron. 



Dumas in 1846 found that on replacing blood serum with a solution 

 of sodium sulphate the blood corpuscles suspended therein still changed in 

 color after shaking with oxygen. 



It was Liebig in 1851 who gave expression to modem thought upon 

 the subject of the respiration in saying, "The absorption of a gas by a 

 liquid is due to two causes, an external consisting in the pressure exerted 

 by the gas upon the liquid, and a chemical, an attraction manifested by the 

 constituent particles of the liquid." 



For complete references to this story, consult "Lecons sur la physiolo- 

 gic," by H. Milne-Edwards, Volume 1, printed in 1857. These volumes 

 treat the subject of physiology with a thoroughness lately thought to be 

 exclusively German. 



