THEORY OF RESPIRATION. 261 



inches of oxygen, which, at the ordinary temperature, 

 weigh rather less than 12 grains (12-2 Eng.). 



If we now assume, that in one minute 10 Ibs. of 

 blood pass through the lungs (Miiller, Physiologic, vol. i., 

 p. 345), and that this quantity of blood measures 320 

 cubic inches, then 1 cubic inch of oxygen unites with 

 9 inches of blood, very nearly. 



According to the researches of Denis, Richardson, 

 and Nasse (Handworterbuch der Physiologic, vol. i., 

 p. 138), 10,000 parts of blood contain 8 parts of per- 

 oxide of iron. Consequently, 76,800 grains (10 Ibs. 

 Hessian) of blood contain 61-44 grains of peroxide of 

 iron, in arterial blood, = 55-30 of protoxide in venous 

 blood. 



Let us now assume, that the iron of the globules of 

 venous blood is in the state of protoxide. It follows, 

 that 55'30 grains of protoxide of iron, in passing 

 through the lungs, take up, in one minute, 6-14 grains of 

 oxygen (the quantity necessary to convert it into perox- 

 ide). But since, in the same time, the 10 Ibs. of blood 

 have taken up 12 grains of oxygen, there remains 5-86 

 grains of oxygen, which combine with the other constit- 

 uents of the blood. 



Now, 55-30 grains of protoxide of iron combine 

 with 34-8 grains of carbonic acid, which occupy the 

 volume of 73 cubic inches. It is obvious, therefore, 

 that the amount of iron present in the blood, if in the 

 state of protoxide, is sufficient to furnish the means of 

 carrying or transporting twice as much carbonic acid as 



