69b 



first range of coagulation with a mixture witli 7 V„ rubber (i. e. 

 abont 25 "j, latex) wiiich had been preserved with formaline. We 

 found the lower limit at 0.0J4N. acetic acid, the upper limit at 

 0.29 N, whilst the own acidity of the diluted latex was 0.015 N. 

 These figures correspond fairly well with ours (tables 2 and 3). 

 Ckossley's lower-limit is somewhat lower and his upper-limit some- 

 what higher, whereby the unknown action of formaline, may liave 

 been of influence. Moreover Ckossley determined the lower limit of 

 the first range of coagulation for dilutions of the above-mentioned 

 latex with 7 7, rubber, and found that, as far as a hundredfold 

 dilution, the total acidity (acetic acid added plus calculated own 

 acidity) decreased with great exactness proportional to the percentage 

 of latex. For dialysed latex with a percentage of 12' „ totally solid 

 substance (i.e. a mixture with about 40 ' „ latex) Chossley ') found 

 the following figures for the lower- and upper-limit of the first 

 range of coagulation: 



The dialysed latex had an acidity of only 0.001 N; all the limits 

 (except the upper-limit with sulphuric acid) are lower than those 

 we found for normal latex, so that the dialysable serum substances 

 in natural latex would have an anti-coagulating action. 



As a criticism of these investigations B. J. Eaton') published a 

 few series of observations with hydrochloric acid, nitric acid, sulphuric 

 acid and acetic acid, which however are very incomplete and did 

 not thiow much light on the phenomena; Eaton found mixtures 

 which remained liquid, but this he attributes to a retardation of 

 the coagulation on account of high dilution, or to an inclusion of 

 the acid in the little lumps on partial coagulation. Eaton denies the 



India Rubber Journal 42 (1911), 1345. 



Bull, of the Dept. of Agric. Fed. Malay States No. 17 (1912), p. 10. 



