66 PARA RUBBER. 



caoutchouc at present is practically permanent, but the amount 

 of water in the latex has largely increased, as you see in the 

 wound response." 



Wright observed at the same Exhibition that some of the 

 Heneratgoda trees when first tapped yielded latex which con- 

 tained only 30 to 50 per cent, of water, whereas when the renewed 

 bark was tapped the latex often contained as much as 90 per 

 cent, of water. Although, as pointed out above, the extra amount 

 of latex produced is said to have kept the yield of caoutchouc 

 constant, the subject merits serious attention. 



The practical man will naturally be desirous of ascertaining 

 to what extent this shrinkage in the caoutchouc content of the 

 latex is likely to occur, and whether it is likely the trees will 

 continue to yield a compensating amount of latex. Other ques- 

 tions which require solution in connection with this problem are, 

 is this decrease of the percentage of caoutchouc due to too early 

 tapping or over-tapping, and can it be remedied by manuring ? 



Rubber is present in latex in the form of minute globules 

 two to three micromillimetres in diameter, similar to the butter 

 fat in animal milk. 



Resinous matter is also present, and this produces the brittle 

 character common to many inferior rubbers. 



Para latex obtained from the trunk of mature trees contains 

 a very small proportion of resin, but it is more abundant in the 

 latex of young trees and young branches. 



The colour of the latex varies in different trees from pure 

 white to pale yellow. This coloration is imparted by the rubber 

 globules, as the solution in which they are suspended is practic- 

 ally colourless. 



When fresh it is quite inodorous and almost tasteless, but 

 acquires a foetid odour on exposure to the air, due to the action 

 of bacteria on the putrescible nitrogenous matter present in the 

 latex. 



Latex on issuing from the tree has almost invariably a 

 decidedly alkaline reaction but later assumes an acid character. 



STORING LATEX. 



Hevea latex when left exposed to the atmosphere rapidly 

 decomposes owing to the action of bacteria, the proteids coagulate 

 and carry down with them the caoutchouc globules. 



