688 



llie coagulation with different salts, will be described in a foiiowing 

 communication. 



We shall discuss in § 8 a few examples of the influence of the 

 original acidity of the latex on the position of the limits of the 

 ranges. 



^ 4. Nitric acid. 



We likewise made serial determinations with nitric acid and 

 sulphuric acid, but less detailed, so that the limits of the different 

 ranges were only roughly determined. For these experiments latex 

 was used from a different group of trees, containing 28 '/, rubber. 

 F'ig. 3 gives the determinations tor nitric acid. The general type is 



0.02 



w 



Fig. 3. 



exactly the same as with hydrochloric acid, buth the liquid and the 

 pappy ranges are smaller. Fig. 3 only goes as far as mixtures with 

 70 ', latex; the top of the pappy range, being with hydrochloric 

 acid at 75 V, latex and about 0.07 N, is found here at a little less 

 than 60 '/„ latex and about 0.04 N. The top of the totally liquid 

 range is comparatively still more displaced towards the right, so 

 that, between both "these tops, a very wide ,, pappy" range is found, 

 in which we separated, by a dotted line, tiiat part wiiere, after 

 two hours a thick or fairly thick pap is formed, from the part 

 still showing fairly liquid mixtures with streaks or a beginning 

 curdling. With nitric acid the upper-limits lie at about half the 

 normality of that with hydrochloric acid. 



In ^ 7 we intend to compare more closely the figures for the 

 four acids, and also discuss more detailed the data for mixtures 

 with 5 and 2 7, latex. 



dj 5. Sulphuric acid. 



The data, which we gathered for coagulation with sulphuric 



