692 



iiuuigles the next daj, wlien witli a iniioli smaller quantity of acelio 

 acid, a coagiiluui tit for use has formed itself. 



To this we add the results of a less complete series of observa- 

 tions, made in November 1922 with latex from the Botanical garden 

 at Biiileiizorg, where a few groups of trees were tapped with a 

 cut over '/» of the circumference. 



This latex contained 37 °, ,, rubber, and had an acidit3' of about 

 0.025 N. We see that the general type is the same, that the lower 

 limits fairly well coincide, but that, with regard to other limits, 

 rather important differences appear, that may be attributed partly 

 to the difference in composition and acidity of the latex, partly 

 however, lo the difference of a|)preciation between the observers. 

 This example illustrates, together with the cases to be discussed in 

 § 8, the restriction we made already in ^ 1, regarding the quanti- 

 tative value of the results. 



TABLE 3. 



Quantity of latex in the mixture in %. 



80 



60 



40 



20 



10 



Beginning lower creamy or 

 pappy range. 



Lower limit first range of 

 coagulation. 



Upper limit first range of 

 coagulation. 



Lower limit second liquid 

 range. 



0.009 

 0.018 



0.010 



0.022 



0.009 



o.on 



0.40 



0.006 



0.009 



0.20 



0.5 



0.0026 



0.0053 



0.083 



0.17 



0.0026 



0.04 



0.066 



0.0020 



0.033 



0.059 



0.0016 



0.023 



0.040 



^ 7. Comparison of the four acids. 



We now intend to compare amongst each other the results, ob- 

 tained with the four acids. Whilst, roughly speaking the general 

 course is exactly the same, we may notify interesting differences 

 and conformities. 



Considering first of all the top and the upper limit of the liquid 

 range, we can use for that purpose the data mentioned in \ 3 — 6, 

 although they refer to two different latices, and the principal obser- 

 vations covered a period of over half a year, because these limits, 

 can only be loughl} determined. So we get: 



