316 BULLETIN OF THE UNIVERSITY OP WISCONSIN. 



the particular sulphates just enumerated, whereas according 

 to the cryoscopic determinations, there is at first a decrease 

 of dissociation with increase of concentration, and then an in- 

 crease of dissociation with increase of concentration. The 

 most dilute solution of MnS0 4 tested (about 0.25 normal) gave 

 a molecular weight of 125.2, corresponding to 2 per cent, dis- 

 sociation, whereas the conductivity method yields about 35 

 per cent. When the molecular weight is 146.5 the dissocia- 

 tion is 3 per cent., the conductivity indicates 20 per cent. 



It is practically useless to make the comparison in the case 

 of CdS0 4 (Table T) for the cryoscopic determinations show no 

 dissociation except in the most dilute solution tested; where- 

 as, as stated above, the conductivity of the solutions is excellent 

 and increases regularly with the dilution. The most dilute so- 

 lution, in which a molecular weight of 185.5 was found would 

 contain the salt dissociated to the extent of 12 per cent. ; the 

 conductivity results yield about 30 per cent. 



Nickel sulphate is practically undissociated according to cryo- 

 scopic determinations (Table 8) when the solution is about ten 

 per cent, strong. The conductivity at about this strength in- 

 dicates 22 per cent, dissociation. The molecular weight of the 

 most dilute solution investigated corresponds to 43 per cent, 

 dissociation^; the conductivity indicates 42 per cent. 



In the case of CoS0 4 the freezing-point indicates no disso- 

 ciation in a solution about 5 per cent, strong or stronger (Table 

 9), whereas the conductivity determinations show about 26 per 

 cent, dissociation when the observed molecular weight is 155.2. 

 In the most dilute solution the molecular weight found is 

 131.8 corresponding to 18 per cent, dissociation; the conduc- 

 tivity indicates about 34 per cent. 



According to cryoscopic determinations FeS0 4 also is un- 

 dissociated in about six per cent, solutions or over (Table 10). 

 When the observed molecular weight is 154.8 the conductivity 

 nevertheless indicates 24 per cent, dissociation. The most dilute 

 solution shows a molecular weight of 135.8 or 12 per cent, dis- 

 sociation; the conductivity indicates 30 per cent. 



