and Magazine of the Ceylon Agricultural Society. 



81 



EXPERIMENTS IN TAPPING CEARA 

 RUBBER. 



In Nyasaland. 

 {From the Handbook of Ny (island.) 



(The African Lakes Corporation, Limited, 

 Chitakali Estate.) 



These experiments were commenced in 

 November, 1906, and are still being continued. 

 Of several systems tried the " full herring 

 bone " has been adopted as the best for trees 

 measuring between 25" and 35" in circumference 

 3 feet from the ground. 



BOWMAN-NORTH WAY NO. 2 



Patent Tapping Knife was selected as the 

 most suitable for trees of this description, 

 both for opening the grooves and paring off 

 the lower edge of the grooves in subsequent 

 tappings. A much simpler knife is, however, 

 being prepared and will shortly be tried. After 

 stripping off the outer covering of thin bark 

 the trees are left for a week or 10 days before 

 tapping. This allows the tissues to recover 

 from the exposure to the atmosphere, and 

 another thin crust will have formed over the 

 surface. By removing the shield and leaning 

 the knife a little to one side a vertical groove 

 is cut, 6 or 7 feet long, running down to within 

 a few inches of the grouud level. Great care is 

 necessary, both in cutting the original grooves 

 and in subsequently paring the lower edge of 

 the grooves, not to cut through the cambium 

 and expose the wood. The cambium, unlike 

 the cortex, does not recover after being 

 incised but produces a knot in the wood, and 

 if badly incised the tree will be killed. 



After making the vertical groove, a small tin 

 spout is inserted at the lower end, under which 

 a vessel is placed to receive the latex. A right- 

 angled triangular piece of tin, the right angle 

 measuring 2' and the sides 17" x 17" approxi- 

 mately, is used as a guide for cutting the 

 oblique grooves which should be at an angle 

 of 45° and 1 foot apart, all leading into tke 

 vertical groove. On trees from 18" to 20" in cir- 

 cumference the "half-herring-bone" system 

 is sufficient. On trees branching out near 

 the ground or measuring over 35 in. in circum- 

 ference it is advisable to have two vertical 

 grooves on opposite sides of the tree, and th e half 

 or full herring-bone system followed. It is ad- 

 visable to leave a space of 2 or 5 inches between 

 the extreme ends of the oblique grooves running 

 from opposite sides of the tree. 



At first it was found that the latex dried very 

 quickly in the grooves, and that only a small 

 portion found its way into the receptacle at the 

 base of the vertical groove. With the assistance 

 of drip-tins this difficulty has been largely over- 

 come. A few drops of liquid ammonia are added 

 to the water in the drip tins to prevent the latex 

 coagulating too quickly. Two smart lads are oc- 

 cupied in collecting the latex and arranging the 

 drip-tins for each tapper. 



THE DRIP-TINS AKE NOT FIXED 



to the trees, but are held by the boy and 

 shifted from groove to groove as the latex ceases 

 to flow. After the latex has ceased to flow in 



all the grooves it is strained through a fine wire 

 mesh and poured into the coagulating bowls. 

 These should be of uniform size and fairly flat, 

 as a thin biscuit is preferred. The latex com- 

 mences to coagulate in a very short time after 

 leaving the tree, especially if it is in small quanti- 

 ties, and is mixed with a considerable quantity 

 of water, which is the case when using the drip- 

 tins. There should be no delay, therefore, in 

 pouring the latex into the coagulating bowls. 

 By 4 p.m. on the same day on which it is tapped 

 the latex has generally all coagulated. It is 

 then rolled on a table, or slanting board, with a 

 hand roller, and constantly washed in clear 

 water. The wet biscuits are then placed on a 

 wire frame, and left to dry in a well-ventilated 

 shed, from which the sunlight is practically 

 excluded. If the biscuits are sufficiently thin 

 they should all be dry and ready for packing in 

 the course of three weeks or a month. 



The table of statistics will show the results 

 obtained from one batch of trees after follow- 

 ing the foregoing system. The trees were 

 tapped about every other day for one month, 

 making 12 or 13 tappings for the month, then 

 allowed to rest a month, and tapped again 

 the following month, and so on until the trees 

 had undergone either a complete cortical strip- 

 ping, or only half, as desired. It is estimated 

 that one-tenth or one-twelfth-of-an-inch is all 

 that should be removed of the cortex in one 

 tapping after the grooves have once been 

 opened. If this rule is followed, it will take two 

 years to entirely strip a tree, after which time 

 operations could probably be continued on the 

 new bark. After nearly two years' experiments 

 the trees are showing 



NO ILL EFFECTS THROUGH EXCESSIVE TAPPING 



except where the cambium has been inadver- 

 tently incised. 



It may be added that the Ceara trees on this 

 estate are of various ages, and had received 

 practically no attention before these tapping 

 experiments were commenced. Many of them 

 had been damaged by bush fires, etc. 



The weight of dry rubber is approximately 

 one-half the weight of wet rubber. 



Ceara rubber biscuits produced as above, and 

 sent home from here, were 



VALUED AT 4s 10D PER LB., 



since which 'time, however, the market for 

 all classes of rubber has fallen considerably. 



Regarding the cost of collecting Ceara rubber 

 in the manner above described the following 

 statistics may be of interest, being compiled 

 from the latest 5 months' results (to September 

 1908) on this estate. One native tapper, with 

 an assistant, taps 50 trees per day, the average 

 quantity of wet rubber obtained daily, taking 

 the average for 86 working days, being 9 '24 

 ounces, yielding 4 - 62 ounces of dry rubber. The 

 cost of collecting and preparing the rubber 

 works out at Is 2£d per lb., excluding cost of 

 European supervision. 



It is anticipated that with the most suitable 

 type of knives it will be possible to tap the 

 trees every alternate day throughout the year, 

 viz., 156 working days ; and— taking the past 86 



11 



