October i, 1902.] 



THE INDIA RUBBER WORLD 



15 



though not mentioned by Senor Ballivian, is probably the de- 

 sire of citizens of the country to profit by locating rubber estra- 

 das and selling them at a profit to foreigners. Only a 

 small fee is required for thus having concessions registered, 

 and if the concessionaire fails to proceed further his loss is not 

 great if the concession lapses. Some years ago a group of 

 Boston rubber men sent an agent to Bolivia who took an op- 

 tion on several rubber properties, paying a forfeit on each with 

 the idea that his principals might determine to acquire the 

 properties and engage in rubber gathering on a large scale. 

 This project was not carried out, however, and a reference to 

 Senor Ballivian's report shows these identical concessions on 

 the list of those registered and abandoned. 

 MAP OF A " SERINGAL." 

 The frequent reference 

 in these pages to esiradas 

 in connection with rubber 

 gathering may make of in- 

 terest some word of expla- 

 nation, with which is pre- 

 sented on this page a dia- 

 gram of a small rubber con- 

 cession embracing 32 ^^/ra- 

 das, giving employment to 

 15 men, lodged in three 

 huts, the whole being con- 

 venient to a water course 

 navigable by a steam 

 launch. This is a rough 

 sketch of a rubber conces- 

 sion actually being worked 

 in Peru, and is probably 

 the first plan of the kind to 

 be presented in print. The 

 word estrada is Spanish for 

 path. A collection of rub- 

 ber trees is called a serin- 

 gal, from the Portuguese 

 name of the Brazilian rub- 

 ber tree " seringa," whence 

 also comes the word serin- 

 guiero — a rubber worker. 

 When a ntvi seringa! \s to 

 be opened, generally in a 

 dense forest rendered al- 

 most impassable by the 

 luxuriant undergrowth, an 

 expert rubber hunter is 

 employed who, starting 

 from a given point, pro- 

 ceeds through the forest 

 until a rubber tree is lo- 

 cated. Calling back to his assistants, he waits until they reach 

 him, blazing out a path on the way and the tree is marked so 

 that it may be recognized. He then proceeds until another tree 

 is found, when the path is similarly extended, and so on until, 

 having gone far enough in his judgment, he turns and proceeds 

 again toward the starting point, still locating and marking rub- 

 ber trees while his assistants blaze out the path. The work of 

 opening the path is then completed, after which it is the duty 

 of each seritiguiero to keep open the estrada (path) which he is 

 detailed to work. The idea is to make the estradas each of a 

 convenient length for one man to tap all the trees included in 

 it, and carry the rubber milk back to the hut and cure it, in 

 one day. Two estradas are assigned to each man, who "works " 



PLAN OF A SERINQAL" IN PERU. 



Hut I — With 15 Estradas, employing 7 men. 



Hut 2— With 12 Estradas, employing 6 men. 



Hut 3 — With 5 Estradas, employing 2 men. 



Total number of trees, 3573. 



them on alternate days. As will be seen, the number of trees 

 embraced in the estradas varies widely, the numbers in the dia- 

 gram ranging from 95 to 160. It will be seen also that this 

 j^^r/«_frt/ embraces three groups of estradas, with considerable 

 open space intervening, the reason for which is that the rubber 

 trees are found in groups, and that in the open spaces indicat- 

 ed, the rubber trees are so scattering as not to repay location 

 and working. 



YIELD OF THE PARA RUBBER TREE. 



To THE Editor of The India Rubber World: Since 

 you have shown so much interest in the subject of the yield 

 of the rubber trees of the Amazon valley, perhaps you may 

 find space for a few more details on this subject. It must be 

 understood that the product of the rubber tree varies greatly 



with its locality and also 

 with its size. For instance, 

 on the Acre it is not un- 

 common to find estradas of 

 100 trees giving 12 to 15 

 kilograms of green rubber 

 — /. e., on the same day as 

 cut. On the Badajos, on 

 the other hand, a similar 

 estrada will yield only 3 or 

 4 kilograms. Besides, the 

 yield from the same estrada 

 will vary at times, and one 

 man may extract 8 or 10 

 kilograms from an estrada 

 that will give only 3 or 4 to 

 another and less skillful 

 operator. 



This is the yield per day. 

 Any attempt to estimate 

 the yearly yield is compli- 

 cated by the varying length 

 of the working season, 

 which may be 60, 90, or 

 even 180 days, in diflferent 

 localities. The same 

 estrada, as a rule, is not 

 worked daily, but every 

 other day. 



It must also be remem- 

 bered that many seringu- 

 ieros adulterate their rub- 

 ber with the latex of the 

 pitch tree, which, when 

 carefully mixed, i fraco of 

 pitch latex to 2 of rubber 

 latex, is not easily detected, 

 the rubber being sold at 

 Mandos as "fine" at market prices. If, therefore, a really 

 good man who cut rubber at night, thereby getting 40 per cent, 

 more, mixed the product with pitch latex, he would get 10+5- 

 = 15 kilograms of rubber from an estrada which would yield 

 only 6 kilograms to an innocent rubber cutter who cut by day- 

 light and sold pure rubber only. Then the statistics of produc- 

 tion usually given do not include "scrap," which is scraped off 

 the trees and mixed together until it is impossible to reckon the 

 total yield for any day, as nearly always the same man works 

 two estradas on alternate days. 



The almost universal practice of heating the latex before 

 smoking in order to hasten the cure of the rubber doubtless 

 has an injurious effect, in detracting from the elasticity of the 



