681 



the soale-size used, i-ecognize ii-regnlar series liquid: ooagiilalion : 

 liquid: coagulation. This narrow strip, the range of small quantities 



Fig. 1. 



of acid, is, with hvdrochloric acid, the only interesting item; tlie 

 remainder of the triangle shows nothing particular, the less water 

 the mixture contains, the harder the coagiilum, while in mixtures 

 with little water and ninoh hydrochloric acid the serum assumes 

 a violet tint. 



The narrow strip along the latex-water side is represented on a 

 larger scale in fig. 2, where the acid is drawn perpendicularly, as 

 ordinate, and expressed in normality (grammolecules HCl per Liter 

 final mixture). 



For quite small concentrations of acid, at any dilution, we first 

 come into the liquid strip, where coagulation has not yet started 

 after two hours. After 24 hours this part shows spontaneous 

 coagulation. At higher acid-concentration (from about 0.007 N) we 

 find after two hours more or less strong curdling or formation of 

 pap, and after 24 hours coagulation. The limit at which after two 

 hours complete coagulation with a clear serum has taken place, is, 



45 



Proceedings Royal Acad. Amsterdaiu. Vol XXVI. 



