Vol. VJI. No lOl. 



THE AGRICULTURAL NEWS. 



47 



FORMALDEHYDE AND ITS INFLUENCE 

 ON FUNTUMIA RUBBER. 



At a niectiiiL,'- oflhc London Section of the Society 

 of Cheniicjil Iiulastiy, the Flucniiaceutlcal Journal 

 rejioits that a paper was read bv Dr. P. Schidrowitz 

 and Mr. F. Kay e on the influence e.^erted on Fantiunta 

 clastica rubber by formaldehyde, when this latter 

 substance is used to coagulate the late.K. 



These two workers have found tliat the rubber obtained 

 from the latex treated by formaldehyde, although less elastic 

 and resilient than that obtained by other means, was extra- 

 ordinarily tough. 1'hey suggest that a rubber of this charac- 

 ter might be particularly suitable for such purposes as the 

 covers of motor tyres, where toughness is of greater import than 

 resiliency, and that in future it may be found desirable to 

 use ditferent methods of coagulation for the same latex 

 according to the purpose for which the. rubber is iateudcd. 



RUBBER CULTIVATION. 

 The cultivation of rubber formed the subject of 

 a paper read some time ago before the members of tiie 

 Grenada Agricultural and Commercial Society by the 

 Hon. W. Grahame Lang. 



lu an i.-iland like tb'enada, where cacao forms the staple 

 crop, it is prohable that if rubber planting is taken up, the 

 form of cultivation adopted will be that of growing the trees 

 through the cacao crojis. Mr. Lang, ,however, point.s out 

 that in all parts of the island, and on ev^ry estate, there are 

 plots of land unsuitable for cacao cultivation, but which woidd 

 in all probaliility give satisfactory result,'), under rubber. 



The valuable information contained, in a letter from an 

 experienced planter of Para rubber in, Bttrma formed the 

 basis of some practical operations in rubber culture, which 

 Mr. Lang has cariied out, and this letter he read before the 

 meeting. The following notes on the -ijequirements of Para 

 rubber, given by Mr. Lang's correspondent, are reproduced : — 



' Para rubber requires an even temperature of 70' to 

 100', but must not fall below 0.3°. , Thrives best with 

 a rainfall of from 80 to IGO inches, but will stand a drought 

 of three months. 



'It will thrive at elevatinns of from, 100 feet up to :i,000 

 feet in suitable localities. 



' The best soil for ]\u-a ntbber is a ;'ich friable loam — the 

 deeper the better. Requires good drainage. 



' If the young plants are raised in a| nursery, the seeds 

 should be sown at distances of 1 foot froju each other. The 

 plants are then .set out when about eighteen months old. The 

 best time to plant out is at the beginning of the rainy .season. 



' When land is under rubber oidy, the trees may be at 

 distances of 15 x lo feet, Init when pla,nted through cacao 

 or other crops, they may be iilauted at distances i.if 20 x '-'O 

 or 25 X 25 feet. 



' Tapping shunid m^l take place till the trees reach a girth 

 of 2 feet at 3 feel frnm the ground. TJiis will usually be in 

 the seventh or eighth year of age." ,| 



Mr. Lang has planted 4,000 (.'astillqj), trees. Some time 

 ago the trees were attacdved with black filight and scale insects. 

 Spraying with kerosene and whale-oil soap emulsion (101b. 

 whale-oil soap in 20 pints of water, and ] 2 pints kerosene, 

 water enough being added before cooling to make the whole 

 up to 25 gallons), liy means of a knap.-^ek sprayer restored 

 the whole to a healthy condition. 



Hcvca seeds to the number of I.IMJO, were obtaini'd tVnm 

 •Ceylon in Xovendjcr 1906, at a e.-t pf £G 5.s., incluilhig 



freight. These were immediately planted out, and 80 per cent, 

 germinated. The young plar^ts grew rapidly, and some were 

 set out in their pennanent^ positions two months after 

 the seeds were sown. The whole were planted out hy the 

 end of March. Owing to th^ dry season a number nl th:' 

 young plants died, but as the 'result of experience, Mr. Lang 

 Avas able to testify to the drought-resisting properties of Jfo'ea 

 lirdiohi'iixix. 



In connexiim with the question of raising the young 

 plants, the reader of the paper expressed his opinion that the 

 method of planting the seed at, stake,in the position the trees 

 were to permanently occupy, was, on account of its cheapness, 

 and the smaller risk of damage to the young plants on account 

 of rough handling, etc., preferable to raising plants in the nurs- 

 ery and afterwards setting them out. 



With rubher, as in the case of 30ung cacao, various 

 catch crops can be raised for the first few years, and Jlr. Lang 

 mentioned that on his estate, cassava, peas, potatos, yam.s, and 

 corn were growing among the rubber trees and doing well. 



The rapid growth of Para rubber trees was referred to, 

 many attaining a height of over 3 feet in ten months. The 

 growth of the roots is equally rajjid, and as the roots keep 

 near the surface and radiate at considerable distance, care 

 nutst be exercised in digging and forking the soil, or harm 

 will certainly follow. Para rubber is not so liable to attack 

 by blight as is Castilloa. 



The question of the yield of rufiber per tree and per 

 acre was discussed in considerable detail by Mr. Lang, and 

 from the figures (juoted from Mr. Herbert Wright's liook on 

 rubf)er, it is evident that a return of 1 to 3 ttt. of rubber per 

 tree per annum should be obtained up to their tenth year, 

 with an increasing yield in subsequent years. 



Some attention is evidently being tiven to rublier plant- 

 ing in Grenada, since ilr. Lang mentioned that he and one 

 or two friends had ordered a-sujijily of 70,000 Hevea seeds. 



FUNCTION OF RUBBER LATEX. 



Mr. W. G. Freeman, B.Sc, F.L.S., Superintendent of 

 colonial economic products at the Imperial Institute, and 

 formerly Scientific Assistant on the staff of the Imiierial 

 department of Agriculture for the West Indies, remarked at 

 a meeting recently held at the Royal College of Science, 

 London, that the exact use of the latex to the rubber tree 

 is still a matter of discussion, but it is one of more than 

 [iiu'cly botanical interest. 



A view which has had a considerable amount of evidence 

 to support it, is that the latex tissues serve as a place of 

 storage for water, to be drawn upon in time of drought. It 

 has been observed in South America that Castilloa rubljer trees 

 gi'owing under moist conditions develop very little latex, 

 i.e. yield very little rubber, Avhile trees growing under drier 

 conditions yield latex more abundantly. If the latex really 

 serves the function of water storage, it would be reasonable 

 to expect that it would be developed to the greater extent in 

 plants living under circumstances which made it necessary 

 for them to store up moisture for periodical seasons of 

 drought. That is to sa}', rubbep plants growing in countries 

 with well-marked dry seasons would have greater inducement 

 to ]_)roduce latex than those growing in continuously humid 

 districts. 



Under the latter conditions, the trees thenrselvcs would 

 thrive and grow very freely,, but they might yield less 

 rubfier, because the .same uece.ssity for moisture .storage does 

 not exist. 



