414 



THE INDIA RUBBER WORLD 



[August 1, 1911. 



A RUBBER PRODUCER FOR THE SUB-TROPICS. 



IT has been the dream of many to be able to cultivate rubber 

 *■ in the temperate zone and perhaps that will yet be done. At 

 all events cultivation is more and more extending towards the 

 frost line. Tonkins rubber tire, the Bleckrodia Toitkineiisis, 

 flourishes where the thermometer for miles gets down to about 

 40 degs. Fahr. It is therefore possible that portions of the rubber 

 tropics, where it is too cool for Hevea. may in time make it 

 available. 



In a comprehensive article in the Bullelin Econoxiiijiii- of the 

 Government of Indo-China, Hanoi. Dr. Ph. Eberhardt and M. 

 Dubard, two official experts 

 have dealth at lengjh with the 

 botanical features of the tree. 

 as well as the questions of cul- 

 tivation, collection and prep- 

 aration. 



THE LATEX .^ND ITS PRODUCTS. 

 1. COLLECTION BY THE NATIVES., 



The appreciation of its value 

 bj' the natives was due to pure 

 accident, a chance knife thrust 

 revealing the fact that the tree 

 in question was a latex pro- 

 ducer. Instead, however, of 

 the latex being kept apart, it 

 was mixed with that obtained 

 from the Ficiis, Autocarpus 

 and other varieties ; the result 

 being a very inferior glutinous 

 product, containing a quantity 

 of resin, which fact depreciated 

 its value upon the European 

 markets. This depreciation 

 being reflected in the reduced 

 limits buyers offered, and the 

 price falling too low to satisfy 

 the natives. They soon ab- 

 stained from tapping those 

 trees. In this way the ex- 

 haustion and destruction of 

 the latter were prevented. 



When collecting latex, the 

 native has only one idea; to 



gather the largest quantity possible. Hence he usually employs 

 barbaric methods, which, if they do not cause the death of the 

 tree, result in a long period of non-production, to enable it to re- 

 pair its injuries. They collect latex from the base of the trunk, 

 up to a height of 8 to 10 feet and also on the large branches. As 

 many incisions as possible are made on the principle that the more 

 incisions the greater the yield. Such, however, is not the case, 

 the yield being less. The lactiferous vessels, being hacked in 

 every direction, no longer permit the normal flow of the liquid ; 

 the circulation being impeded and the latex containing a very 

 large quantity of organic substances. 



I'REP.\RATION OF THE RUIiBKR. 



In whatever way the tapping has been affected, tlic native re- 

 ceives the latex in small receptacles of interlaced bamboo. This 

 mode of collection leads to the introduction of foreign sub- 

 stances. These bamboo receptacles are then conveyed to the 

 adjacent village, or to a water-course, where they are placed in 

 a saucepan of water until it boils, being then removed in coagu- 

 lated form. The latex of Blcckrodea coagulates very quickly, 

 that process being facilitated by the motion to which it is sub- 

 jected in transport. ^^^^^^ ^^ collection. 



The late.x can be collected twice a year, in the spring and 



General View of a Rleekrodea Cut by the Natives. 



autumn, but the natives are disposed to limit their efforts to the 

 second period, between the end of August and the end of 

 N'ovember. At this time the yield is considered to be more 

 abundant. The Bleckrodca is extremely sensitive to the varia- 

 tionof the seasons ; while its yield varies according to the latitude 

 in which it is being developed. 



CLIMATIC influences. 



The most suitable time for tapping the Blcekrodea Tonkinensis 

 has not yet been definitely determined. The yield seems closely 

 related to the atmospheric conditions. In the Bac-Kan region, 

 where tlie autumn and winter seasons are cold, tapping in No- 

 vember and December resulted 

 in a very limited flow, while 

 that operation in May and 

 June gave in two hours equal 

 to about 12 ounces per tree, 

 from trees of moderate age, 10 

 inches in diameter. December 

 tappings in the basin of the 

 Black River, considerably 

 further south, were, however, 

 as copious as those of the Bac- 

 Kan region in May and June. 

 The influence of temperature 

 on the yield of latex to be 

 accurately determined, would 

 require observations running 

 over an entire year, at the 

 different altitudes and latitudes 

 where the tree is met with. 

 Another point calling for in- 

 vestigation is the time of day 

 most suitable for tapping. 



LATEX FROM A CHEMICAL STAND- 

 POINT. 



Blcckrodea latex is a slightly 

 thick liquid, of the ' shade of 

 coffee with milk, recalling the 

 latex of the Ficus elastica (e.x- 

 cept as regards its color") and 

 like the latter coagulating very 

 rapidly and without the aid of 

 chemicals. The product of its 

 natural coagulation, is of grey- 

 portion very rapidly taking a 

 Chemical investigation 

 while its nerve and 



ish brown color ; the whit 

 brownish tint when exposed to the air. 

 reports its elasticity to be very good, 

 adhesiveness are stated to be perfect. 



The composition of rub1)er from the Blcckrodea Toitkineiisis is 

 as follows : 



Density 0.955 



Water 28.32 



Ashes 0.62 



Actual rul)bcr 60.76 



Resins 3.67 



Foreign sulistances, difference 6.63 



It is remarked that the quantity of actual rubber may appear 

 small, hut this is due to the large proportion of water (28.32%). 

 This percentage of water is attributed to the recent manufacture 

 of the slab submitted for analysis, it having been made only 

 three days previously. 



After dealing with various suggested improvements in tapping 

 and other operations, the question of the chemicals to be used 

 is taken up. On this subject it is stated that of various acids, 

 sulphuric acid has always given the best results. Acetic acid 

 seems to produce a dissociation of the surface of the globules, 



