936 Experiments 



40°, under a vacuum, one finally obtains almost all the oxygen 

 and all the C0 2 contained in the blood; but it takes a long time, 

 the successive pump strokes bring only small quantities of gas, 

 there comes at the same time water vapor in which the carbonic 

 acid is dissolved again at the time of the condensation, and finally, 

 a more serious matter, a small quantity of oxygen may be consumed 

 during the operation. On the contrary, at the temperature of 

 boiling water, all the gases are immediately extracted by the 

 vacuum, and it has sometimes happened that I extracted all of 

 them with a single stroke of the pump. 



Nitrogen. According to the researches of Fernet, 100 volumes 

 of blood, at 15°, can dissolve 1.4 volumes of nitrogen. I have often 

 found figures a little higher than this, which signifies nothing, 

 because some bubbles of air may have been left in the whole ap- 

 paratus; but I have also found some a little lower, and this is more 

 interesting. Setting aside possible causes of error, we find in this 

 the suggestion that the blood, as it passes through the lungs, is not 

 sufficiently agitated with the air to become saturated with the 

 gases which it is capable of dissolving. 



This becomes a certainty when we consider the results of the 

 experiments on the gases of the blood of animals placed in com- 

 pressed air. In fact, nitrogen is very far from following Dalton's 

 law, because at 10 atmospheres, for example, I found as a maxi- 

 mum only 11.4 volumes (Exp. CLXXXIII). 



I shall return in a moment to this important observation. 



Oxygen. The proportions of oxygen which we have found in 

 the same volume of blood, in animals of the same species and in 

 equally good health, have varied within limits of astonishing 

 extent. 



I am presenting here a table as much for carbonic acid as for 

 oxygen, using, of course, only experiments made on animals breath- 

 ing ordinary air at normal pressure. I placed in parentheses and. 

 I do not include in the average of the analyses those in which the 

 animals were sick or breathed under abnormal conditions: the 

 necessary specifications are given in the column of observations. 



And so, eliminating extraordinary circumstances, the extremes 

 were for oxygen 24.0 (Exp. DCLXVI) and 14.4 (Exp. CCLXXX) . 

 There are 8 analyses giving from 14 to 15, 9 giving from 16 to 18, 

 29 giving from 18 to 20, 25 giving from 20 to 22, and 9 from 22 to 24; 

 the general average was 19.4. But we see that I was right to take 

 often in the course of this book as an average the proportion of 20 

 volumes per 100. 



