687 



about 0.11 N, i.e. at the ii|»|)er-liinit of tlie liquid rauge (see fig. 2), 

 the number of small liiuips increases and the Brownian movement 

 decreases, and at 0.13 N hardly any particles move, and only very 

 few show Brownian movement. At 0.14 N the decreaming begins, 

 which, at 0.15 N, leads into the range of coagulation. From 0.10 

 to 0.15 N therefore, there is a gradual transition from "free parti- 

 cles with Brownian movement" into lumps, particles jet free but 

 not moving, and decreaming. Whether perhaps the few little lumps, 

 which are found in the second liquid range, were formed by a local 

 excess of acid during addition, was not examined. 



If we keep a liquid from the middle part of the second liquid 

 range, e. g. 2 '/, latex with 0.06 N. hydrochloric acid, in a high 

 cylindric glass, no decreaming takes place within the first few 

 weeks, but the Brownian movement gradually decreases. After two 

 monlhs most of the particles iiave joined into small lumps, a fe^v 

 consisting of two or three, but most of them consisting of a great 

 number of globules, so that, after that time, only a fairly small 

 number of free particles remain in Brownian movement; yet only 

 part of the rubber is decreamed, and superficially the liquid is still 

 equally white. 



We regret we were unable to examine, whether in the second liquid 

 range the negative ciiarge, which the rubber-globules show in the 

 original latex, had given place to a positive one, as required by 

 the theory of ,, change of charge" '). Some experiments concerning 



1) Gf. F. Powis, Z. Phys. Chem. 89 (1915), 105. 



H. R. Keuyt, these Proceedings IT (1914). 615. and 19 (1917), 1021. 



