Gases of the Blood 641 



Subchapter V 



THE QUANTITY OF OXYGEN WHICH CAN BE 



ABSORBED AT DIFFERENT BAROMETRIC PRESSURES 



BY THE BLOOD DRAWN FROM THE VESSELS 



The analyses of the gases contained in the blood of living ani- 

 mals subjected to pressures lower than one atmosphere gave me 

 for oxygen, as I remarked before, results far different from the con- 

 clusions which could have been drawn from classic researches, 

 particularly those of M. Fernet. 



Magnus had already shown that when blood is placed under the 

 belljar of the pneumatic machine and the pressure is gradually 

 diminished, gases begin to escape only at very low pressures, and 

 the blood turns dark (that is, loses a considerable part of its oxy- 

 gen) only in the neighborhood of 10 cm. of mercury. 



M. Fernet had intended, as we saw in the historical part of this 

 book, to find out whether the gases of the blood were in a state of 

 simple solution or bound in a chemical combination. In the first 

 case, he said with reason, the capacity of the blood for these gases 

 should be proportional to the barometric pressure, following the 

 well-known Law of Dalton. In the second, there will be no relation 

 between this law and the proportion absorbed at different pres- 

 sures. And if a gas is partly dissolved and partly combined in this 

 liquid, it will be possible, by a simple calculation, to determine the 

 proportional value of these two parts. 



Now,— speaking only of oxygen— by agitating blood in contact 

 with this gas under pressures varying from normal pressure to 647 

 mm., M. Fernet reached this double conclusion: 1) that there is 

 dissolved in the blood plasma a quantity of oxygen (coefficient of 

 solubility at 16°, that is, volume of gas dissolved per unit of volume 

 of liquid under normal pressure: 0.0288) nearly equal to that which 

 is dissolved in pure water (coefficient of solubility at 16°, according 

 to Bunsen: 0.0295) ; 2) that the blood corpuscles combine chemically 

 with a quantity of oxygen, independent of the pressure, much 

 greater than the preceding, because it is on the average 0.0958 per 

 unit of volume of blood. We see then that, according to these ex- 

 periments, the barometric pressure, in these various modifications, 

 can hardly modify the proportion of oxygen contained in the blood. 

 In fact, it could act only on the simply dissolved gas, which is to the 

 combined gas in the proportion of 0.0288 to 0.0958, that is, of 1 to 3.3, 

 when the absorption experiments are performed with pure oxygen. 



