CARBON MONOXIDE OF BLOOD 213 



lyzing with about 300 c.c. of water, and adding 2.5 c.c. of the 

 potassium ferricyanide solution. After twenty minutes, 25 c.c. 

 of the potassium cyanide solution are added and the mixture is 

 diluted to the mark. The blood pigment value of this solution 

 is known from the gasometric determinations and the unknown 

 may be compared directly with it or suitable dilutions of the 

 standard may be made. 



Calculation of Results. An example will make this clear. 



Strength of standard 15 gms. of hemoglobin per 100 c.c. 

 of blood. 



Comparison of cyanhemoglobin in colorimeter; Standard 

 10, Unknown 12. 



Unknown has if of 15.0 or 12.5 gms. of total blood pig- 

 ment per 100 c.c. 



Gasometric determination of hemoglobin 10 gms. per 100 

 c.c. 



Therefore, sample has 12.5 10 or 2.5 gms. of methemo- 

 globin per 100 c.c. 



CARBON MONOXIDE IN BLOOD 



Method of Van Slyke and Salvesen l 



Principle. Oxygen and carbon monoxide are set free from 

 their combination with hemoglobin in the blood by addition of 

 ferricyanide and both gases are removed with the help of a Torri- 

 cellian vacuum in the Van Slyke apparatus for blood gas analysis. 

 The oxygen is absorbed in the apparatus by alkaline pyrogallate 

 and the volume of residual carbon monoxide is measured directly 

 at atmospheric pressure, a correction being made for the small 

 and constant amount of nitrogen gas physically dissolved by blood. 



Procedure. The procedure is, up to the time when the 

 expelled gas is measured, exactly the same as that for the oxygen 

 method described by Van Slyke (see page 124, this Manual), and 

 is therefore unnecessary to repeat it here; the same amount of 

 blood and the same solutions are used, and only the shaking has 

 to be continued a little longer before a constant reading is ob- 

 tained. This takes about two to three minutes and is a little 

 1 Van Slyke and Salvesen: Jour. Biol. Chem., 1919, 40, 103. 



