and Magazine of the Ceylon Agricultural Society.— March, 1912. 



277 



usual form taken by the final product at the 

 present day. In the preparation of the other 

 varieties of commercial rubber named above 

 certain modifications must be introduced into 

 the process. 



In the preparation of crepe, the latex, after 

 being strained in order to remove any small 

 particles of bark or other mechanical impuri- 

 ties, is poured into enamelled pails or pans, 

 and a small quantity of acid added. Acetic 

 acid is most commonly used, its chief ad- 

 vantage being that the quantity introduced 

 can be varied between comparatively wide limits 

 without affecting the result, so long as the 

 excess of acid is removed from the rubber by 

 thorough washing. Recently the use of hydro- 

 fluoric acid has been recommended as this 

 substance is said to possess strong antiseptic 

 properties. It may here be noted that any acid 

 will effect coagulation if added in the right 

 proportion, and so will many ether chemical 

 substances, but the utmost care must be taken 

 not to introduce any material which would be 

 likely to affect the product during its mani- 

 pulation into rubber goods. By the use of a 

 slight excess of acetic acid coagulation can be 

 effected in about 15 to 20 minutes, and the 

 blancmange which the rubber resembles at this 

 stage is washed by passing it between steel 

 rollers under a stream of water. From this pro- 

 cess the rubber emerges in long thin corru- 

 gated strips having rather the appearance of 

 crepe. The next operation is drying, during 

 which the rubber is either hung up in slightly 

 heated rooms, or enclosed in vacuum or hot 

 air drying machines. The former method of 

 drying occupies several days, whereas by the 

 use of machines the moisture can be got rid 

 of in a few hours. Finally, the rubber is milled 

 once more between slightly warmed rollers. The 

 amount of this final milling requires to be 

 carefully regulated, and this is a matter for 

 co-operation and correspondence between the 

 planter and the manufacturer, since the latter 

 requires to know the exact physical condition 

 in which the rubber leaves the' estate factory. 

 The condition most popular at the moment is 

 the thick corrugated strip of rubber known 

 as blanket crepe. If it is desired to export 

 the rubber as block, several strips can be pressed 

 together at this final stage. 



For preparing sheet or biscuit the latex must 

 be set in shallow pans. Coagulation takes place 

 rapidly on the addition of acid, but for con- 

 venience of handling the clot is allowed to 

 stand for a few hours until it sets firm. As 

 much water as possible is then squeezed out 

 of the rubber, either by machine rollers or by 

 hand, and the drying takes place in hot rooms, 

 occupying from a week to ten days, if the sheet 

 or biscuit does not exceed three-sixteenths of 

 an inch in thickness. In some factories a further 

 curing operation is added to those already des- 

 cribed, the rubber being hung up in an atmos- 

 phere impregnated with creosoted smoke until 

 the antiseptic properties of the creosote are to 

 some extent imparted to the rubber. Several 

 inventions are undergoing trial, which have in 

 view the common object of treating the latex 

 with creosoted smoke and effecting coagulation 

 at the same time, 



Rubber is packed in wooden boxes holding 

 about a hundred- weight or a little more. It is 

 highly important that the interior of the 

 boxes should be smoothly planed, and that no 

 packing material should be used which can 

 stick to the rubber, since the smallest amount 

 of grit or foreign matter adhering to the sur- 

 face materially affects the value of the product. 



The yield of rubber from individual trees 

 varies enormously, a difference) of over 1,000 

 per cent having been found between the best 

 and worst trees of quite a small group at 

 Henaratgoda. The average per acre from well- 

 grown trees of the same age at the same ele- 

 vation is, however, fairly constant, and the 

 yield per acre is the safest method of calculat- 

 ing probable returns. A fairly conservative 

 estimate for Ceylon would be 100 lb. per acre 

 by the end of the seventh year, 150 lb, during 

 the eighth year, and 250 lb. during the ninth 

 year, with an increase up to about 400 lb. per 

 acre in subsequent years. 



Oil from Rubbee Seeds. 



It has been suggested that the collection of 

 the seeds which are now produced in large 

 quantities on Hevea plantations may form the 

 basis of a profitable minor industry, since 

 the kernels contain about 40 per cent of an 

 oil which is similar to linseed oil, and has 

 been favourably teported upon by chemists 

 at home. The suggestion to lease out the right 

 of collecting the seeds does not appear a very 

 happy one, owing to the opportunities for 

 theft of rubber which such an arrangement 

 would afford. But at times of abundance the 

 collection could be readily carried out on the 

 estate by children too small to take part in 

 the tapping and other regular work. 



Hevea seeds weigh about 71b. per thousand, 

 and the cost of collection this year was given by 

 the Superintendent of the Peradeniya Experi- 

 ment Station asunder half a cent a pound. As 

 the kernels represent approximately half the 

 weight of the seeds, a ton of kernels will 

 not cost more than Rs.22'50 to collect under 

 these circumstances. To this must be added 

 the cost of decorticating the seeds, and for 

 this purpose machines are under trial, with 

 which it is hoped to perform the operation at 

 a comparatively small expense. It is possible 

 that the development of this subsidiary industry 

 will form an appreciable addition to the value 

 of rubber estates in the future. 



COCONUTS IN JAMAICA. 



In Jamaica, not only have coconuts not been 

 cultivated or manured, but they have been 

 treated in the roughest possible fashion ; a com- 

 mon practice is to make steps and stairs on 

 them by chopping footholds on them, so as to 

 make it easy to climb them. A. coconut tree 

 should live and bear for 100 years, but when 

 chop holes are made in it the water enters, fer- 

 mentation is started and the coconut begins to 

 rot. Holes and trenches for manure should not 

 be too near the mature palm. If the tree is full 



frown, six feet would be too near, 8 to 12 feet 

 etter, 



