and Magazine of the Ceylon Agriculturist Society. 



108 



180VC. it is converted into a thick liquid much 

 resembling molasses. Therefore, it might be 

 supposed that the residue mentioned above also 

 consisted principally of resinified caoutchouc. 



"My suspicion was confirmed when treating 

 the latex by a mixed process of skimming and 

 spontaneous desiccation. % 



" By this method I obtained a much higher 

 percentage of rubber and only a small residue, 

 consisting likewise of a yellow and viscous 

 matter. However, the rubber was less elastic 

 than that obtained by coagulation in the hot 

 bath. This is not surprising, seeing that the 

 rubber prepared by the latter process contains 

 all the components of the latex and the root 

 sap (excepting the greater part of the water), 

 and, besides, I had not been able to strain the 

 liquid, having no metal net nor adequate strainer 

 with me. 



Percentage of raw Loss by 

 Processes employed. rubber per cent. drying per 

 Green. Dry. cent. 

 Coagulation over fire .. 2-90 1-870 35-51) 



„ in the hot bath .. 3*51 2-415 33'U9 

 Skimming and spontaneous 



desiccation .. 13'00 6-360 51-60 



" In order to determine the 



PERCENTAGE OF PURE CAOUTCHOUC OBTAINED 



by these process, I analysed the samples of 

 'Ecanda' rubber prepared in Benguela, in the 

 chemical laboratory of the Institute de Agro- 

 nomia e Veterinaria, with the following re- 

 sults : — 



Rubber obtained by Coagulation in the 

 Hot Bath. 



Caoutchouc . . . . 88-025 per cent. 

 Resins ... .. 4'725 ,, 

 Substances soluble in water .. l'lOO ,, 

 „ „ in alcohol at boil- 

 ing point l - 30O ' „ 

 Water .. .. 1-082 

 Impurities not determined .. 3768 „ 



Rubber obtained by Skimming ant- Sponta- 

 neous Desiccation. 



Caoutchouc .. .. 71*925 per cent. 



Resins .. .. 3*300 



Substances soluble in water . . 2-950 ,, 

 ,, ,, in alcohol at boil- 



ing point 1*385 ,, 

 Water .. .. 3-154 



Impurities not determined .. 16'926 ,, 

 " Thus I obtained by coagulation in the hot 

 bath 2*125 per cent of chemically pure caout- 

 chouc, calculated from the weight of the fresh 

 root, and by the mixed method of skimming and 

 spontaneous desiccation •4*574 per cent of pure 

 caoutchouc : that is, I obtained by the latter 

 process more than twice the quantity of pure 

 caoutchouc than by the first. 



" It follows, therefore, that, of the processes 

 which I tried, it was the process of skimming 

 and spontaneous desiccation by which I ob- 

 tained the best result. The great drawbacks 



t To extract the rubber by this method I proceeded as 

 follows :— I poured the liquid obtained by the crushing of 

 the ' Ecanda ' roots into enamelled iron dishes so as to 

 form a layer 1 cm. thick. After a while in every one of the 

 dishes and adhering to their sides a skin of rubber formed on 

 surface of the liquid. This skin I removed, and so I went 

 on for two days— the duration of the experiment— new 

 skins continuing to form, but every time less thick. Then 

 the production of skins ceased. But to make sure whether 

 the liquid still contained caoutchouc I left it in the dishes 

 until the evaporation was complete, which was the case 

 five days after the commencement of the experiment. As 

 the dishes were exposed to the air, and the latex some- 

 what caught the sun, I believe that the little yellow and 

 viscous residue which formed consisted to a small extent 

 of resinified rubber. 



inherent in that method are, however, aggra- 

 vated when it is applied to the treatment of a 

 liquid resulting from the crushing of the Ecanda 

 root and that makes it hardly practicable. 



GUAYULE RUBBER INDUSTRY IN 

 MEXICO. 



Adverting to the article on pp, 632-4 of the 

 Board of Trade Journal of the 28th March, 1907, 

 giving particulars of the Guayule Rubber in- 

 dustry of Mexico, H.M. Legation there now 

 reports, on the authority of an American expert 

 who has been studying the industry, that there 

 is only about 400,000 tons of guayule now in 

 existence in the Republic, either standing in its 

 native soil, or at the extraction plants, or on 

 the way to the plants for extraction. The 

 scarcity has bocome so marked that the most 

 remote districts are now being searched for the 

 plant, and the Bolson de Mapimi district is 

 being thoroughly gone over, and the guayule 

 gathered and delivered under contract to the 

 Continental Rubber Company of Meiico. This 

 district, lying between the Siena Mojada and 

 worreon, is practically the last remaining one 

 There there is guayule in any quantity, and the 

 remainder of the 400,000 tons has long since 

 been purchased by various extracting companies 

 at from 21. 10s. to 71. 10s. per ton. The pur- 

 chases at the lower prices were made before the 

 landowners realised the value of the shrub or 

 wero aware of the improbability of the plant 

 reproducing itself in a short time. It is a 

 practical certainty, according to the expert, that 

 with the consumption of the existing supply, 



THE INDUSTRY WILL GO INTO DECAY. 



It had been hoped that experiments would be 

 made by persons interested, in the production, 

 planting of seed and joining it with some 

 kindred plant to accelerate its growth, so that 

 a period of but four or five years would be neces- 

 sary for the plant to reacli the proper size for 

 extraction. This, it is said, could be effected by 

 grafting the guayule upon some kindred plant, 

 the roots of which would furnish the tops with 

 a greater flow of sap, and consequently result in 

 more rapid growth ; but this nas not, to the 

 expert's knowledge, yet been attempted, al- 

 though, in his opinion, it is the only hope for 

 the future of the industry. — Board of Trade 

 Journal, June 11. 



THUMB-NAIL PRUNING OF PARA 

 RUBBER. 



Tavoy, June 28th. 

 Dear Sir,— 1 do not quite understand Mr 

 W VV Bailey's letter in the last issue of the Tro- 

 \neal Agriculturist, with reference to "thumb- 

 nail" pruning para rubber. One would infer that 

 the trees he refers to, and the method adopted in 

 Malaya, is to slice off the tops of young saplings. 

 This, I take it, is not what Mr Herbert Wright 

 recommends, or ever recommended. As the name 

 clearly seems to imply, what I suppose should 

 be— and is — done is to nip off with the thumb 

 and first finger nails the extreme tip of each 

 sapling which has reached 10' or 12', or such 

 other height as the owner fancies is the correct 



