and Magazine of the Ceylon Agricultural Society, 



397 



BITINGA RUBBER. 



FROM " RAPHIONACME UTILIS." 

 Considerable interest has been aroused re- 

 cently by the discovery in Portuguese West 

 Africa of a plant, bearing various native names, 

 such as " bitinga," " ecanda " and " raarianga," 

 the tuberous roots of which contain a rubber- 

 yielding latex. Several specimens of the rubber 

 and of the roots of the plant from which it is 

 obtained have been received at tho Imperial 

 Institute from the Mozambique Company. The 

 samples of rubber consisted of three ruughly 

 cylindrical pieces, which differed considerably 

 in quality owing to the inclusion of varying 

 amounts of impurities. The cleanest specimen, 

 which, however, contained an appreciable amount 

 of impurity, consisted of pale yellowish brown 

 rubber exhibiting good elasticity and tenacity. 

 The other two pieces were darker in colour ; one 

 of them contained a considerable quantity of 

 vegetable impurity, whilst the other wasimpreg- 

 nated with fine sand. In both cases, however, 

 the physical properties of the rubber were fairly 

 good. The light-coloured rubber was chosen for 

 analysis as more likely to represent a well-pre 

 pared product; this gave the following results:— 



Sample as 

 received. 

 Per cent. 



Composition 

 of dry rubber. 

 Percent. 



Moisture ... l'O — 



Caoutchouc ... 76'8 77 '6 



Resin .. 9'0 Sri 



Proteid.s ... U'6 0"6 



Insoluble matter ... 12 6 12'7 



Ash (included in " insoluble 

 matter") ... 711 7'1S 



These results indicate that the rubber would 

 be of good quality, so far as chemical composition 

 is concerned, if it were not for the presonce of 

 the large amount of insoluble impurity which 

 considerably reduces the precontage of true 

 caoutchouc. The amount of resin is somewhat 

 high, but the percentage of proteid is exception- 

 ally low. A portion of this sample was valued by 

 commercial experts at Is. to Is. 3d. per lb., but they 

 Btated that the rubber, if clean, should be worth 

 3s. per lb., or more, as compared with line hard 

 Para rubber at -Is. lOd. per lb, on the same date. 

 Roots. 



A number of the tuberous root6 of the plant 

 were also received and submitted to examination. 

 The tubers are turnip-fhaped, and vary up to 

 5 - 5 inches in diameter and 4 inches in height. 

 They are covered with a dark brown scaly bark. 

 Many of the roots had decomposed more or less 

 during transit, but a number were still sound, 

 and yielded latex quite freely on incision. 



Two samples of the fresher roots with un- 

 broken bark were selected for analysis; specimen 

 A was a single large tuber weighing about 6 

 ounces, whilst B consisted of two smaller 

 tubers which together were approximately equal 

 in weight to A. The results of the examination 

 were as follows ;— 



A. P. 

 Calculated on roots as received. 

 Moisture .. 86'88 88-87 



Rubber .. 1-52 l - 04 



Insoluble residue, resin^ 



Rubber (on dry roots) 



Tho yield of rubber from the tubers as received 

 is therefore very low (i"0 to To per cent) owing 

 to tho largo amount of water which they contain, 

 and as these tubers must have dried consider- 

 ably during transit, the freshly-collected roots 

 will probably furnish much less than the 

 figures recorded above. The acreage yield 

 of rubber from the dry material is however 

 fairly high, viz. 10'5 per cent. 



Identification of the Bitinga Plant. 



.Specimens of the " Bitinga " roots were for- 

 warded to Kew by tho Mozambique Company 

 with a view to the identification of the plant, and 

 ilowering specimens were obtained in March of 

 this year. The plant proves to be a new species 

 of Raphionacme of the natural order Asclepia- 

 daoete and has been named Raphionacme utiles 

 Brown and Stapf. ...It is probable that the Bi- 

 tinga plant thus identified is identical with the 

 11 Eeanda" or 11 Marianga " plant discovered by 

 Professor Geraldes, during a journey to the 

 Upper Zambesi, in 1904-05. According to this 

 author the Ecanda or Marianga plant occurs in 

 tho sandy treeless plains (ankams) of Bailundo 

 and Biho and on the sandy steppes between tho 

 rivers Quanza and Zambesi, at an altitude of 

 4,000 to 5,000 feet. The natives in these 

 districts prepare rubber from the roots by 

 cutting them into slices, which are then spread 

 on the ground and exposed to the sun, whereby 

 the exuded latex is coagulated. The rubber thus 

 formed is rolled into small cylindrical pieces, 

 about 5 inches long and j inch in diameter. The 

 rubber so prepared is stated to be of good ap- 

 pearance, but it usually contains considerable 

 quantities of earthy impurity ; thus, one sample 

 examined contained only 45"8 per cent, of true 

 rubber, and 51 '4 per cent of impurities. 



Professor Geraldes found that the most prac- 

 ticable method of obtaining rubber from the 

 fresh roots was to cut them into pieces and sub- 

 ject the latter to pressure. In this way the 

 latex, much diluted with the sap of the roots, 

 was obtained. The yield of liquid on expression 

 amounted to about 77 per cent, of the weight of 

 fresh roots used. From this liquid, the rubber 

 can be prepared either by heating it or by ex- 

 posing it to the air. The maximum yield of rub- 

 ber obtained by Professor Geraldes in his 

 experiments was a little less than - 5 per cent, 

 from the fresh roots, which is less than half tho 

 amount found in the tubers received at the Im- 

 perial Institute. 



It is impossible, until further particulars are 

 available, to express any opinion regarding the 

 probable value of the Bitinga plant as a com- 

 mercial source of rubber. Definite information 

 is required as to (1) tho rate of growth of the 

 plant; (2) the age at which the tubers can best 

 be utilised for the preparation of rubber; (3) 

 the weight of fresh roots which can be obtained 

 per acre ; (4) the average yield of rubber ; and (5) 

 the best method of obtaining the rubber from 

 the roots. It is understood that the Mozambique 

 Company is conducting experiments in East 

 Africa in order to determine these points, and 

 to ascertain whether tho plant is likely to repay 

 cultivation, — Imperial Institute Bulletin N<>. 1 of 

 1908. 



