316 Appendix III. "Reaction' of Blood 



APPENDIX III. ON THE HYDROGEN ION CON- 

 CENTRATIONS OF REDUCED BLOOD 



Measurements have been made by Peters (Physiol. Soc. Proc., Jan. 1914) of the 

 hydrogen ion concentration of Barcroft's blood subjected to various pressures of CO 2 . 

 The blood was completely reduced, and the following curve was obtained. The result 

 was nearly but not quite the same as that obtained by Hasselbalch and his colleagues, 

 whose admirable work on the reaction of the blood may be read parallel with the 

 later chapters in this book. 



C0 2 pressure mm. 10 20 30 40 60 80 100 



P H 8-11 7-67 7-52 7'39 7'30 717 707 699 



Till further experiments have been performed Peters would not insist on the 

 absolute accuracy of his measurements but there seems no doubt about their com- 

 parative accuracy. 



We already have (Chapter V) a relation between the C< > 2 pressure in Barcroft's 

 blood and A", the equilibrium constant in the equation 



y Kx n 

 100 \ 1+A>- ' 



We may therefore directly compare A' and the hydrogen ion concentration : 



Log A' 3-40 3-20 3-00 4-80 4-60 4-40 4-20 4-10 



K x , x=-2-60 2-80 3-00 3-20 3-40 3-60 3-80 3-90 



P H -8-10 7-933 7-72 7'59 7'42 7-25 7-075 6-99 



The comparison is instructive enough for it appears that the product of C H 

 is constant as shown by the fact that the figures in each column of the last 2 lines 

 in the above table add up to 10"8'l. Should this relation prove on further 

 examination to be substantiated, Hill suggests that it is evidence of actual chemical 

 combination between the hydrogen ion and the haemoglobin. The hydrogen ion 

 would then have two actions: (1) a tendency to cause the globin molecules to 

 aggregate and (2) an actual union with the haematin portion. 



We are not so much concerned with the theoretical qiiestion as with the fact that 

 we can state a figure for P,, at the various places at which we have measured K in 

 Barcroft's blood. 



K P H 



Normal -00029 -7 '29 



Carlingford after climb of 1000 feet in 45 miu. -00024 7 -22 



30 -00017 7-09 



Cold'Olen 45 7'14 



Margherita Hut arrive -00013 7 '02 



