86 THE RUBBER INDUSTRY 



These figures are equal to a total yield of 70*2 ounces 

 of dry rubber, or an average of 1*75 ounces for each of 

 the forty trees tapped during the six days' trial. The 

 density of 670 c.c. to i pound of dry rubber is extra- 

 ordinarily high, and it compares with an average of 

 1,341 c.c. at the Ceylon Government Gardens of 

 Henaratgoda, according to official returns published 

 in May, 1913. 



In all the foregoing experiments coagulation of the 

 latex was obtained by the use of a solution of acetic acid, 

 preference being given to this method in order to enable 

 the rubber to be dried without the long delay necessary 

 when the coagulation is effected by smoke. 



The records kept by Mr. da Costa at the Santa 

 Maria estate, in the Madeira district, furnish some 

 useful information concerning density and yield of 

 latex, and they may be accepted as an accurate basis 

 on which to calculate returns for that section of the 

 Amazon Valley. On this property the quantity of 

 latex extracted in the month of June, 1913, from gouge 

 tapping with the double and single herring-bone system, 

 was 329,000 c.c. ; this latex was coagulated by the 

 smoking process, and yielded 528 pounds of wet rubber, 

 equal to 291 pounds when dried, not including any 

 lump or scrap. This gives a density of 1,038 c.c. to 

 i pound of dry rubber. On the same property one 

 collector obtained a daily average of 4,000 c.c. from 

 170 trees, tapping with the gouge on the single-V 

 system during the first three months of the season, an 

 equivalent of 23*5 c.c. per tree per day; this should 

 give 3*3 pounds of first-quality rubber per tree during 

 a tapping season of 150 days, and in addition about 



