584 THE GASES OF THE BLOOD 



obtaining methaemoglobin in crystalline form (its acid solu- 

 tion produces a brown color). A fluorine combination of 

 methsemoglobin may also be obtained in crystalline state, 

 by mixing a solution of methsemoglobin with concentrated 

 solution of sodium fluoride-ammonium sulphate, and chilling 

 to C. 14 



BLOOD GASES 



Technic of Blood Gas Analysis. The technic of blood 

 gas analysis belongs among the most difficult and yet the 

 most carefully worked out chapters of physiological technol- 

 ogy. To some extent it has been dealt with in the previous 

 lecture; but here, too, reference must be limited to a few 

 brief statements, and the various handbooks must be con- 

 sulted for details. 15 



As the union between haemoglobin and oxygen is broken 

 in a vacuum, it is possible to withdraw the latter from the 

 blood by means of an air-pump. The distinguished role 

 accorded Pfliiger's blood-gas pump in the history of physi- 

 ology is a matter of common knowledge. More modern ap- 

 paratuses of this kind have been proposed by Zuntz, Bohr, 

 and by Buckmaster and Gardner. 16 More recently the pump 

 methods have given way more and more to the chemical 

 method of blood-gas analysis, which is not only much more 

 satisfactory and simpler, but has in addition the great ad- 

 vantage of being adapted to the employment of very small 

 quantities of blood. As already stated, the oxygen is set 

 free from the blood by potassium ferricyanide, and the 

 method, perfected by Haldane, Barcroft, Brodie, Hamill 

 and Franz Miiller, works with a remarkably high degree 

 of exactness. 



The tension of the gases in the blood may be determined 



14 J. Ville and Derrien, Compt. rendu, 140, 1195, 1905. 



"Literature upon the Methods of Blood Gas Analysis: A. Lowy, Handb. 

 d. Biochem., 4', 17-24, 1908; Franz Miiller, Handb. d. biochem. Arbeitsmethod., 

 3, 555, 1910; 5, 1027-1034, 1912; Bohr, Tigerstedt's Handb. d. physiol. 

 Methodik, 2, 1, 1910; J. Barcroft and P. Morawitz (Physiol. Instit., Cam- 

 bridge), Deutsch. Arch. f. klin. Med., 98, 223, 1908. 



18 G. A. Buckmaster and J. A. Gardner, Jour, of Physiol., 40, 373, 1910. 



