224 THE CAUSE OF MOUNTAIN" SICKNESS 



Htif ner has given us the formula x rrrzr f or reckoning the 



2 saturation, where cc = the percentage in reduced haemoglobin, 

 p = the partial pressure of oxygen in mm. Hg, and k is a 

 constant. From their results Loewy and Zuntz reckon the value 

 of k to be 0-04. 



Using this formula and constant, they calculate that normal blood 



O tension 

 % of atm. 



63-97 tension 

 in mm. Hg 



5638 



49-77 



42-6G 



35-55 



28-44- 



21-33 



14-22 



7-77 



Saturation of Hb 

 FIG. 9. Average Dissociation Curve of OHb in Human Blood (Locivy}. 



shaken with ordinary air at body temperature is only about 88 per 

 cent, saturated with oxygen. We must remember that part of the 

 barometric pressure is due to vapour tension, and this lessens the 

 tension of oxygen in the lungs where the air is saturated with mois- 

 ture. Further, we must remember that the percentage of oxygen 

 in the alveolar air is not that of the air but only 13-14 per cent. 

 Taking these two factors into account, it comes out that the 



