LATEX. 65 



Seeligmann, loc. tit., gives the following results of an analysis 

 made of fresh latex collected from a Hevea tree, twenty-five 

 years of age, in Brazil during the year 1888 : 



Per Cent. 



Elastic matter 32.00 



Nitrogenous organic matter (putrescible) 2.30 



Mineral salts, sodic and calcic (no magnesic) 9.70 



Resinous bodies - traces 



Water, slightly alkaline 55.0 to 56.00 



This latex was obtained from a gash made in the trunk of 

 the tree about 20 inches from the ground. Its density was 0.919 

 at 57.2 Fahr., and the caoutchouc globules measured on an 

 average 3.51 micromillimetres. 



Kelway Bamber found fresh latex obtained from cultivated 

 mature Hevea trees when first tapped during more or less dry 

 weather contained : 



Per Cent. 



Caoutchouc - 32.00 



Nitrogenous matter 2.03 



Mineral 9.07 



Resinous 2.03 



Water faintly alkaline - 55.56 



100.69 



It would be interesting to know the cause of the compara- 

 tively large difference between the caoutchouc content of the 

 latices examined by Faraday and Seeligmann. It is significant 

 that after cultivated Hevea trees have been tapped several times 

 the percentage of caoutchouc in the latex has been found to 

 considerably decrease. In a series of tapping experiments con- 

 ducted at the Singapore Botanic Gardens, a tree with a girth of 

 112 inches gave from the first period of tapping (spiral method) 

 265 \ oz. of latex, from which 9 Ibs. of rubber were obtained ; 

 from the second period of tapping, one month later, the tree 

 yielded 433 oz. of latex which only gave 4 Ibs. 15 oz. of rubber. 



Kelway Bamber is reported to have stated at the Ceylon 

 Rubber Exhibition (held in September 1906) : " In all the latex 

 sent to me recently and from what I hear from planters, the 

 latex does not now equal that portion (i.e., 32.00 per cent, of 

 caoutchouc), and the caoutchouc has in some instances gone 

 down to 1 5 per cent, or less " ; and, " I think the amount of 



E 



