« 



400 Dr. S. B. Schryver and Miss N. E. Speer. 



only extended the hospitality of publication to me for the last 22 years, but 

 has also afforded me assistance from the Government Grant placed at its 

 disposal. 



It is now my good fortune to have been able to found a Eesearch Institute, 

 from which the present paper forms the first instalment of work. It is my 

 wish that the facilities of this Institute should be available to research 

 workers from all countries. In this I am attempting to carry out the 

 tradition of my country, which, so far back as 25 centuries ago, welcomed 

 scholars from all parts of the world within the precincts of its ancient seats 

 of learning at Nalanda and at Taxilla. 



Investigations dealing with the State of Aggregation. Part IV. — ' 

 The Flocculation of Colloids by Salts containing Univalent 

 Organic Ions. 



By S. B. Schryver, D.Sc, and Nita E. Speer. 



(Communicated by V. H. Blackman, F.R.S. Received June 18, 1918.) 



(From the Department of Plant Physiology and Pathology, Imperial College of 

 Science and Technology.) 



Theory and Scope of the Researches. 



In an earlier paper* the action of salts in a heterogeneous system was 

 discussed, and the factors which exert influence on the state of hydration and 

 aggregation of the " colloid phase " were summarised. The present communi- 

 cation deals with only one of these factors, viz., the surface-tension of the 

 solutions and the relationship between this property and the capacity of salts 

 for flocculating colloids. 



The mechanism by means of which this flocculation is produced is still 

 a matter of considerable controversy. The view which appears, up to the 

 present, to be most widely maintained is that the precipitation depends, in 

 the first instance, on the adsorption of the active (precipitating) ion by the 

 colloid. According to Freundlich, who is mainly responsible for what may 

 be termed the adsorption hypothesis,! the action of the ions can be explained 



* Schryver and Hewlett, ' Roy. Soc. Proc.,' B, vol. 89, p. 361 (1916). For Parts I-III 

 of this series see 'Eoy. Soc. Proc.,' B, vol. 83, pp. 96, 113, 119 (1910). 



t Freundlich, ' Zeitsch. Physikal. Chem.,' vol. 73, p. 385 (1910) ; Freundlich and Gann, 

 ' KoUoid-chem. Beihefte,' vol. 8, p. 108 (1916). 



