629 



concentration present is still proportionately three times less than 

 with AlCij. 



A start has already been made with investigations to get a proper 

 insight, particnlarlj in this question of the irregular series. 



8. Finally it should be pointed out that the previous considera- 

 tions also give an explanation of the fact often stated by us that in 

 the case of Al-salts we can determine the limit value much more 

 accurately than w^ith salts of uni- or bivalent metals. Two tubes with 

 ASgSg sol. which contain Al in concentrations situated 17o above 

 and below the limit value, respectively exhibit after shaking a quite 

 clear and a turbid fluid respectively. In the case of bivalent cations 

 we must, so as to make quite sure, take the difference somewhat 

 larger and \ery much so for a univalent ion. It is self-evident 



dE 

 that the cause lies in the fact that — (g charge, c concentration of 



dc 



coalescing ion) for A1-- is > for Ba- and this again > for K*. 

 Utrecht. June 1914. van 't Royy- Laboratory. 



(November 7, 1914). 



