Section 45. Summary. 11 1 



the degree of ionization, have been calculated (see table 27, section 44). 

 Specific volume data for the more concentrated solutions have also been 

 presented (in table 18, section 38). 



A study of these data has led to the following conclusions : 



(1) At all temperatures the equivalent conductance (A) and ioniza- 

 tion (y) of the two tri-ionic salts, potassium sulphate and barium nitrate, 

 vary with the concentration according to approximately the same law 

 as do those of silver nitrate and of the other two di-ionic salts, potas- 

 sium and sodium chlorides, previously investigated. For, in the case 

 of all these five salts, in order that functional relations of the form 

 C(A A) = const. X(CA)" or C(l y)= const X(Cy) n may express 

 the results, values varying only between 1.40 and 1.52 must be assigned to 

 the exponent n, while according to the mass action law its value should 

 be 2 for di-ionic and 3 for tri-ionic salts. 



(2) The principle that the relative velocities of different ions acted 

 upon by the same electric force approach equality with rising temperature 

 is strikingly exemplified in the case of the bivalent S0 4 = and Ba ++ ions. 

 Since bivalent ions owing to their double charge are acted upon by twice 

 the electric force when in the same electric field, their equivalent con- 

 ductance would become twice as great as that of univalent ions when 

 the resistance to their motion through the solution was the same; and 

 in this case the equivalent conductance of a completely ionized salt con- 

 sisting of a univalent and a bivalent ion would become 1.5 times that of 

 a uni-univalent salt. Now, our results show that at 18 the salts potas- 

 sium suphate and barium nitrate have equivalent conductances at zero 

 concentration which are 1.02 and 0.90 times respectively that of potas- 

 sium chloride, but that at 306 the corresponding ratios are 1.54 and 1.16. 



(3) The ionization values at all temperatures for silver nitrate agree 

 within a few per cent with those previously derived (in Part II) for 

 sodium and potassium chlorides; and the values for potassium sulphate 

 and barium nitrate also agree with each other within a few per cent; 

 thus confirming at high temperatures and for relatively small ionization the 

 rule that most salts of the same ionic type have roughly the same degree 

 of ionization. 



(4) The ionization of all the salts investigated decreases steadily with 

 rising temperature, the decrease being more rapid the higher the tem- 

 perature and the greater the valences of the ions of the salt. Even where 

 the ionization has become small, as it has at the higher temperatures, the 

 simple principle still holds true approximately that the fraction of the 

 salt un-ionized is proportional to the product of the valences of its ions. 



