CHAPTER VII 

 YIELD AND DENSITY OF LATEX 



Average yield varies in different districts Yield on the Madeira, 

 Puriis, and Jurua Yield on the upper rivers and in Bolivia 

 Experiments with gouge tapping Variation in quantity and 

 quality of latex Tests for density on the Madeira and Puriis 

 Further tests Records kept at Santa Maria, River Madeira- 

 Records kept at Sevastopol, River Puriis Exaggerated reports of 

 yields of trees. 



'"T^HE average yield of rubber- trees in the Amazon 

 A Valley varies to a marked extent in different dis- 

 tricts, and, in the absence of accurate statistics extend- 

 ing over any lengthy period, the average quantity of 

 latex and amount of dry rubber produced can only be 

 calculated approximately for most sections of the 

 country. In the case of the properties on the Rivers 

 Madeira and Purus more detailed information is avail- 

 able, as a result of a series of experiments and tests 

 conducted under competent supervision in 1912 and 

 1913, in order to ascertain the density, yield and pro- 

 portion of rubber in comparison with returns obtained 

 in Ceylon and elsewhere in the Orient. These experi- 

 ments were prompted also by a desire to obtain definite 

 knowledge as to the relative conditions of latex extracted 

 by the use of the machadinho compared to that procured 

 by gouge tapping on the herring-bone system, and for 

 this purpose tests were carried out on both forest - 

 grown and planted trees in districts with many different 



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