CHEMISTRY. 347 



The formula suggested by Noyes and Johnson was finally adopted 

 and found to give concordant results. Subsequently an approxhiia- 

 tion formula worked out by Randall was used. This formula gave 

 Ao values agreeing within the limits of accuracy of the method used 

 and entailed much less laborious calculation than the Noyes formula. 



The limiting conductivities of all the sodium salts studied have 

 been calculated by one or the other of the above formulae, and from 

 them it is possible to obtain the values for the acids themselves. 



Dr. Ordeman has completed the study of the relative dissociating 

 power of free and combined water begun by him last year. Experi- 

 ments carried out in this laboratory some years ago had shown that a 

 marked physical difference exists between free and combined water, 

 as illustrated by the different absorption power for light of solutions 

 of hydrated and non-hydrated salts. It therefore seemed probable 

 that a measurable difference in the dissociating power of free and 

 combined water would exist. Carefully conducted experiments, 

 using the conductivity method, have shown this to be highly probable. 

 Paired isohydric solutions of hydrated and non-hydrated salts were 

 used as solvents for the various electrolytes studied. It was found 

 that for every pair of solutions in such solvents — the one solution of 

 a hydrated, the other of a non-hydrated salt — the suppression of the 

 ionization of the added salt by the anions of the solvent-solution was 

 more prominent in the case of the hydrated solution. In other words, 

 the increase in conductivity caused by the addition of the same 

 amount of an added salt to each of a pair of isohydric solvent-solu- 

 tions, the one non-hydrated, the other hydrated, is always greater 

 in the non-hydrated solutions; this points to a greater dissociation 

 in the non-hydrated than in the hydrated. Furthermore, it may be 

 pointed out that the suppression of the ionization of the hydrated 

 salts added was much greater than that of comparable solutions of 

 non-hydrated salts in both isohydric solvent-solutions. From these 

 results it seems justifiable to conclude that the water of hydration 

 in the solutions of hydrated salts must possess less ionizing power 

 than the uncombined water, in which case the various salts added as 

 solutes would be dissociated to a lesser degree, the effect being greater 

 the greater the concentration, since more combined water would then 

 be present. The hydrated salts used as solutes are less dissociated 

 than the other added salts, because water of hydration would then 

 exist in both of any pair of solvent-solutions. However, the disso- 

 ciation is always less in the case of the hydrated salt of any pair of 

 solutions because of the less dissociating power of the water of hydra- 

 tion already present in that solution. 



It should be noted, however, that the conclusions from this work 

 can be regarded as only tentative because of its preliminary nature. 

 Further work on the subject should be done in order to ascertain the 



