102 



The Supplement to the Tropical Agriculturist 



THE PLANT AND ITS PROPERTIES. 



The ' Bitinga ' plant agrees very well with the 

 description and figures given by Prof. Geraldes, 

 of the ' Ecanda ' plant, and there is practically 

 no doubt that they are identical. It is a new 

 species of Rcqjluonacmc, nearly allied to B. Wcl- 

 ivilschii, Schlechter& Rendle, a native of Central 

 Angola, and is described below as Raphionacmc 

 utilis, Brown and Stapf . It differs from all the rub- 

 ber plants already known insofar as it is a dwarf 

 herbaceous plant with a fairly large subterres- 

 trial tuber abounding in caoutchouc. As prac- 

 tically all our knowledge concerning the dis- 

 tribution, properties of the plant, and the pro- 

 cess of working it, is at present confined to 

 what we may learn from Prof. Geraldes' article, 

 a translation of the more important paragraphs 

 is given here : 



"The interest attaching to the 'Ecanda' or 

 ' Marianga 1 rests not only on the fact that we 

 have to deal here with a new species and more- 

 over one which is morphologically different 

 from all the other known rubber plants, but 

 also, and more especially, as I believe, on its 

 capacity of producing first-class rubber and 

 the facility of working it, in which respect it 

 has no rival. The ' Ecanda : is a herbaceous, 

 stemless plant with a tuber-shaped root fairly 



LARGE AND RICH IN LATEX. 



" From experiments made in the interior of 

 Benguela in order to find out the best process 

 for the preparation of Ecanda rubber, I came 

 to the conclusion that the only rational and 

 practical method is by crushing the roots and 

 treating the latex thus obtained by one of the 

 processes of ' lato-borrachificacao externa ' (co- 

 agulation of the latex after extraction). It is 

 evident that the method of first extracting the 

 latex very much simplifies the preparation of 

 rubber and clearly results in considerable 

 economy. The 'Ecanda' or 'Marianga'* is 

 found in the treeless, sandy and alluvial 

 tracts (anharas) of Bailundo and Bihe and 

 the Xanes (sandy and troeless tracts) of 

 the region between the rivers Kwanza and 

 Zambese (Ganguellas), the home of the Ota- 

 rampa (Carpodinus chylorrhir.a). \ Those tracts 

 occur locally, as a rule near the headwaters and 

 along the banks of the rivers, occupying, some- 

 times, vast areas, and it is in their drier parts 

 that the 'Ecanda' thrives. The altitude of the 

 region where the ' Ecanda ' grows is from 4,000 

 feet (Ganguellas) to 5,500 feet (Bihe). 



" As stated, the laticiferous tubes of the 

 ' Ecanda ' are found spread all over the pulp of 

 the root ; at the same time the latex, being very 

 concentrated, coagulates rapidly in contact with 

 air. It is therefore 



NOT POSSIBLE TO EXTRACT IT ENTIRELY FROM THE 

 ROOTS BY MEANS OF INCISIONS. 



" The extraction of the rubber direct from the 

 roots necessitating, as it does, first prolonged 

 boiling and then crushing, followed by repeated 



" ' Ecanda ' is the name by which the species (which 

 occurs in Bailundo and Bihe) is known to the Bailundos 

 and Bihanos, and it is, I assume, identical with the spe- 

 cies known to the Lutxases (Ganguellas) as ' Marianga.' 



t I suppose that the 'Ecanda' also occurs in the Xana 

 of Xifumage (an affluent of the Zambesi which I have 

 crossed) a vast, treeless, sand and humus plain to the 

 north-east of the district of Benguela. But when I tra- 

 versed it, the natives had set fire to it as they are used 

 to: do, and the whole vegetation was destroyed. 



washing is not practical since, apart from tho 

 tediousness of the process, it implies necessarily 

 the use of chemical agents in order to secure the 

 complete separation of the caoutchouc from the 

 pulp by the disorganisation of its tissues. And 

 even so, unless dissolvents are used for the puri- 

 fication, the rubber remains somewhat impure 

 as may be well imagined. 



"But to my great satisfaction I made sure 

 that it was possible to extract the latex of the 

 ' Ecanda ' (although mixed with the sap of the 

 roots) with great ease by means of simply 

 crushing the roots. To extract the latex pro- 

 ceed as follows : — After having washed the 

 roots well, cut them into several pieces at a 

 right angle to their greatest diameter and 

 subject them to a slight pressure in a copying 

 press. When the liquid ceases to flow rai«e the 

 top of the press, turn the pulp and subject it 

 anew to slight pressure. Repeat these opera- 

 tions as long as the liquid comes out yellowish 

 and without streaks of white, that is to the 

 point when the latex is completely extracted 

 and only root sap continues to flow. 



" To obtain this result it is necessary to 

 extract from the roots, on the average, 77 "7 per 

 cent, (of the weight) of the liquor; hence the 

 latex is much diluted (1"5 per cent, of the liquid 

 extracted from the roots should on the average 

 be pure latex). Having found a practical process 

 for extracting the latex, I tried now to deter- 

 mine the best method for coagulation. I 

 obtained good coagulation with alcohol or 

 brandy whenever the latex was not very much 

 diluted. This process is evidently not econo- 

 mical as the coagulating agents are dear. . . . 

 Acetic acid, sulphate of aluminium and 

 potassium, phenol and chlorate of sodium do 

 not act on the latex diluted with root sap. 

 . . . Other coagulating agents I was not 

 able to try. ... It is, however, probable 

 that coagulation of the latex of ' Ecanda ' may 

 be obtained with other agents, even when it 

 is diluted with root sap. The process of skim- 

 ming loaves much to be desired, since, in my 

 experiments, I have never succeeded in extract- 

 ing by this method more than half of the 

 caoutchouc contained in the latex. ... I 

 also studied- the effect of heat on the liquid 

 obtained by pressing the roots of the ' Ecanda. 

 ' If the liquid is subjected direct to the action 

 of fire, a skin forms on the surface, like that 

 on boiled milk, consisting of caoutchouc. If 

 this skin is removed in the measure as it forms, 

 its production ceases after some time, and when 

 at length the liquid is completely evaporated, 

 a copious yellow and viscous residue is left. By 



SUBSTITUTING A HOT BATH FOR DIRECT FIRE 



and proceeding in the way just described, there 

 also remains a yellow and viscous residue, but it 

 is less copious. In this way I obtained a greater 

 percentage of caoutchouc which was of greater 

 elasticity than that produced by coagulating 

 direct over fire. "Thus by using heat as the 

 coagulating agent I always obtained beside the 

 caoutchouc a more or less copious residue of a 

 yellow and viscous substance. Now, it is well 

 known, that generally caoutchouc, if subjected 

 to temperatures above 35° C, gradually loses its 

 elasticity, and turns viscous, until at 170* to 



