334 BULLETIN OF THE UNIVERSITY OF WISCONSIN. 



normal solution the molecular weight is about 61.7 correspond- 

 ing to 64 per cent, dissociation; the conductivity results yield 56 

 per cent. Silver nitrate (Table 21) also shows an increase 

 of molecular weight with increase of concentration, which 

 agrees qualitatively with the dissociation theory. The most 

 dilute solution tested yielded a molecular weight of 102.8, 

 corresponding to a dissociation of 65 per cent. ; the conduc- 

 tivity results yield about 67 per cent., — an acceptable agree- 

 ment. For a normal solution the molecular weight is about 

 110 corresponding to 54 per cent, dissociation; the conductivity 

 determinations indicate 52 per cent., — again a very fair agree- 

 ment. It happens, then, that the behavior of potassium and 

 silver nitrates agrees much better with the demands of the dis- 

 sociation theory at the boiling-point of the solutions than at 

 the freezing-point 1 . It will be noted that these nitrates behave 

 alike, and that solutions of KC10 3 apparently exhibit a be- 

 havior similar to that of the nitrates. 



The sulphates (Tables 22 to 29) again show great similarity 

 in their general behavior. In the case of MgS0 4 (Table 22) 

 the molecular weight begins with a value somewhat above the 

 theoretical, — which indicates no dissociation; then it increases 

 at first with the concentration and finally it decreases with in- 

 crease of concentration after having passed through a maximum, 

 the values in the strongest solutions becoming less than the 

 theoretical. There is clearly no irregularity in the conduc- 

 tivity values (Table 2) to even suggest such a behavior. What 

 has been said about MgS0 4 applies also to ZnS0 4 (Table 23), 

 NiS0 4 (Table 26) and CuS0 4 (Table 29). The same general 

 behavior is also exhibited by MnS0 4 (Table 24), CdS0 4 (Table 

 25), CoS0 4 (Table 27) and FeS0 4 (Table 28), except that 

 the molecular weights of these salts, while first increasing, and 

 then decreasing, with the increase of concentration, always 

 remain above the theoretical values. As table 2 shows, there 

 is nothing in the conductivity results to lead one to expect 

 such a behavior. A comparison of the freezing-point results 

 (Tables 4 to 10) with those obtained by the boiling-point method 



1 Compare for Instance Arrhenius' table 1. c. 



