ON THE OSMOTIC PRESSURES OF CALCIUM PERROCYANIDE SOLUTIONS 323 



The meaning and numbering of the columns are the same as in Table I., with 

 the exception that for the potassium salt column (4) is omitted because the salt, 

 which was purchased as Messrs. Kahlbaum's purest, was not systematically analysed* 

 for its water content. 



In the following table the mean values are given, and the columns are numbered 

 and have the same significance as in Table II. 



TABLE IV. 



Observed 



equilibrium 



pressure. 



atmospheres 



19-25 

 13-52 

 9-19 

 5-41 

 2-93 



(5.) 



Osmotic 



pressure 



(Bovi.K's law). 



atmospheres 



7-95 

 5-29 

 3-39 

 1-84 

 0-93 



It will be noticed that these results are such as would be expected on the 

 dissociation hypothesis ; the greater the dilution the greater the ionisation, until at 

 the greatest dilution there is apparently dissociation into about three ions or 

 molecules. 



A few experiments were made with strontium ferrocyanide to see whether the 

 same anomalies (see p. 321) obtained as those shown by the calcium salt. The salt 

 was purchased from Messrs. Kahlbaum and purified by recrystallisation as in the case 

 of the calcium salt. 



Analyses gave the following results : 



* An analysis of the salt gave 12-81 per cent. H 2 O. Theoretical 12-78 per cent. 

 t The sample was taken from a lot which was known to have been overdried. 



2 T 2 



