RUBBER 405 



trees frequently reach a height of 60 to 80 ft. and a diameter of 12 to 30 in. 

 The tree flourishes best in damp, rich soil and where the temperature 

 ranges from 89 F. to 94 F. at noon and never falls below 73 F. at night. 

 The trees are seldom tapped until they are twelve to fifteen years of 

 age, because they yield an inferior grade of rubber if tapped earlier. 

 The rubber fluid or latex is collected during the dry season from June to 

 February and, if properly carried on, the tapping is not injurious. Great 

 efforts have recently been made to conserve the rubber forests, and prac- 

 tices which are destructive to the trees are being abandoned. It has 

 been determined that the latex runs most freely in the early morning. 

 The " seringuero," or rubber tapper, equipped with a small basket and a 

 quantity of tin latex cups, goes out along the " estradas " or pathways 

 cut through forest to each rubber tree. He makes a blow or incision 

 with a hatchet and attaches the cup to the bark at the base of the incision 

 to receive the latex, by either using clay as a plaster or by slipping the 

 cup underneath the bark. The tapper uses his judgment as to how many 

 cups each tree should carry. There may be up to 20 cups on each tree. 

 The cups hold only a few ounces each. The tapper comes back to empty 

 the cups into a pail the same day or next day, depending on how rapidly 

 the trees are flowing. The latex secured from this tapping contains 

 about 30 per cent of rubber and the average sized tree will yield about 10 

 Ib. of rubber per year. The latex is collected, brought to camp and con- 

 verted to the crude rubber state in the following manner. A fire is built 

 of dry sticks and oily palm nuts (Attalea excelsa) and the natives make a 

 piece of wood about 3 ft. long fashioned like a paddle, which is dipped 

 in the latex and held over and revolved in the smoke of the fire. The 

 smoke of the fire is usually controlled through a narrow bottle-like neck. 

 As the milky fluid becomes dried and hardened on the paddle, the process 

 is continued until a large ball or " biscuit " weighing 5 to 6 Ib. or more is 

 formed. The smoke has the peculiar property of firming and curing the 

 latex. A skilled native is said to make from 4 to 6 Ib. of rubber per hour 

 by this method. Other forms of sticks are commonly used as well as 

 the paddle-like form. This " wild " Para rubber, although containing 

 many impurities and 15 per cent of moisture, is said to be the finest 

 rubber product obtainable. The scrapings from the tree are mixed with 

 the residue from the fire pots and collecting receptacles and made into 

 large balls called " negro-heads." These contain from 20 to 35 per cent 

 of impurities such as chips, bark, water, twigs, etc. 



2. The " ule " or " caucho " rubber of Central America and Peru, 

 generally called " centrals " in the trade is derived from Castilloa elas- 



