412 



ION SERIES AND PROTEINS. Ill 



are held together by electrostatic forces and that these forces are 

 stronger in the case of a hydrogen ion which is free from electrons than 

 in the case of a Na ion where the positive nucleus is separated by two 

 shells of electrons from the valency electron of the oppositely charged 

 ions by which it is held. For this reason the tartaric acid, or the 

 oxalic acid, anion combines with proteins in the form of a monovalent 

 acid tartrate ion while we should expect the anion of disodium tartrate 

 or disodium oxalate to be a bivalent anion. Hence the tartrate and 

 oxalate anions should act like the sulfate anion when disodium tar- 

 trate or disodium oxalate are added to a protein solution. This is 

 confirmed, as Fig. 12 shows. The curves for the depressing effect of 

 Na2 oxalate and Nao tartrate practically coincide with the curve for 



the depressing effect of Na2S04 on the viscosity of gelatin solution? 

 except in concentrations greater than m/256 where disodium tar- 

 trate and disodium oxalate cause also a depression of the hydrogen ion 

 concentration (Table III) and where therefore the curves for these 

 two salts drop more rapidly than the curve for Na2S04. Hence diso- 

 dium oxalate and disodium tartrate act like Na2S04, while, as Fig. 8 

 shows, monosodium tartrate, monosodium citrate, and monosodium 

 phosphate act like NaCl (if the necessary corrections for pH are made). 

 The osmotic pressure, viscosity, and swelling of Na gelatinate should 

 be depressed by the cation of a salt and the more so the higher the 

 valency of the cation. Fig. 13 shows that this is true for the swelling 

 of Na gelatinate of pH about 9.3. The molecular concentration in 



