i 7 8 



PHYSICAL CHEMISTRY 



MgSO. 



1/2 Oa01» 

 1/2 MgCla 



iKNOi 



Fig. 30. Freezing point lowering of weight normal solutions. The 

 scale is too small to show the increased ionization at very great dilution. 

 The curve for MgS0 4 approximates that for cane sugar and dextrose 

 and is near that for 1/2 K 2 S0 4 . The curve for KC1 may be used for 

 KOH, NaOH and NaNO s . The curve for NaCl approximates that for 

 NH,C1 and is near that for Na,S0 4 for the higher concentrations. 



proteids. This combination dissociates to a greater extent than 

 C0 2 and the excess of HC0 3 ions so produced diffuse into the 

 plasma, leaving the interior of the corpuscle electropositive. 

 The CI ions of the plasma are attracted by this electropositive 

 charge and enter the corpuscle. Only a small part of the C0 2 

 added takes part in this exchange, however, and a larger propor- 

 tion of it is stored in the corpuscles than in the plasma. This 

 follows from von Limbeck's observation that the osmotic pres- 

 sure of the corpuscles increases more than that of the plasma, 

 causing the corpuscles to swell, due perhaps to the fact that 

 alkali within the corpuscles binds the C0 2 . This alkali is sup- 

 posed by some investigators to be ordinarily combined with pro- 

 tein, but in the presence of an excess of C0 2 , joins the latter. 



This experiment shows that, at least in the presence of an 

 excess of C0 2 , the erythrocytes are permeable to CI ions. Ham- 

 burger and van Lier (1902) have shown by the same method 

 that the erythrocytes are permeable to S0 4 and N0 3 ions. 



Henderson and Spiro (1908) made a model of this process. 

 A beaker of Na 2 C0 3 solution represented the plasma, a parch- 

 ment paper tube filled with Na 2 CO s + protein representing a 



