Vol. XII. No. 290 



THE AGUICULTUICAL NKWS 



1X1 



The latter, with tlie remaining 24 per cent, of undecorticated 

 nuts, wen- |ia«sed tlirrmyh the macliine a second time, after 

 which only 2 per cent remained undecorticated and 3 

 per cent partly shelled The nuts behaved very similarly 

 to oil palm nuts during alielling iJetter lesult^ would 

 j)roViably ba obiained after ascertaining by e.xperiment the 

 correct speed at which the machine i-hould be run for 

 decorticating grugru nuts 



KKM.M:k> 'As altc;idy indicated there is no doubt that 

 gru gru kernels in good condition would find a ready 

 market in the I'nited Kingdom at prices apprc^ximating tfi 

 those of palm kernels, if they can be ulfered in commercial 

 t|uantities, i.e., in shipments of from 50 to 100 tons at a time. 

 It is diflicult to interest oilseed crushers in products which 

 cannot be obtained regularly in quantity, and information 

 should therefore be furnished to the Imperial Institute as 

 to whether it is probable that commercial consignments of 

 the kernels could be supplied from the West Indies. 



'With reference to the question as to whether it would 

 be more profitable to export the fat rather than the 

 kernels from the West Indies, it may be stated that 

 gru gru fat of good quality should realize about the same 

 price as palm kernel oil which is at present worth about £45 

 per ton in the I'nited Kingdom (April 1913); it might, 

 however, fetch rather less than this as it is a little .softer than 

 average palm kernel oil As already mentioned, however, 

 technical trials on a large scale would be necessary in order 

 to decide the exact value of tlie fat, snd it would seem 

 desirable in the first place to begin by -hipping the kernels 

 from the West Indies The kernel.s alone should be exported, 

 as the whole nuts would not be readily saleable in Europe.' 



THE PREPARATION OF PLANTATION 

 PARA RUBBER. 



In continuation of the article in the last ifsue of the 

 the A'jrioilliirul Xtus, llulletin No. ] 7, l)epartment of 

 Agriculture, F. M.S, proceeds with a consideration of the 

 darkening or oxidation of raw rubber samples and the 

 methods of prevention Although colour has no connexion 

 with strength and quality of a sample, it is stated to be 

 an important commercial character, in that the colour of 

 certain rubber goods may be relatively of more importance 

 than strength. Darkening is due to the action of an 

 enzyme, 'oxidase', and its action can be increased by some 

 salts and inhibited by others. 



Black latex is referred to first. It has been suggested 

 that this abnormal appearance is produced by trees attacked 

 by white ants {Terines yestroi), or by other pests. Observa- 

 tions made by the author show that the cause is not of 

 parasitic origin, the real explanation being that the blacken- 

 ing is due to the presence of a high proportion in the latex of 

 oxidizable substances. Sodium bisulphite arrests the oxida- 

 tion, though the best procedure is to avoid contact with the 

 air as far as possible by diluting the latex in the coagulating 

 pans, and by immersing the coagulum under water. Another 

 method of producing pale rubber is by steaming. A short 

 treatment by this process destroys the oxidase. 



Turning to the subject of moulds and bacteria on rubber, 

 it is fibserved that one sample examined contained a mixture 

 of a red organism — liacillu." prodigiosan — and a yellow yeast 

 (Sarcina). Several antiseptic substances were tested, but it 

 was found that the best method of preventing the growth of 

 organisms is that of smoking, to be referre<l to later 



The action of carbon dioxide as a co;)gulaling agent is 

 next considered. When carbc^n dioxide was passed directly into 

 latex no cosgulation took [>lace. The value of this gas, 



however, as an atmosphere in whith to dry the rubber was 

 found to be very great, since carbon dioxide inhibit.% 

 oxidation and produces a pale rubber. It further prevent* 

 the growth <A mould and bacteria. It was found that drying 

 in the presence of the inert gas is effected more rapidly by 

 the slightly elevated lemperature when the gas is generated 

 from burning charcoal. 



Patei't coagulants, dealt with in the next section, are not 

 recommended for general use. 



After describing certain special processes of coagulation, 

 which aim at imitating the Amazonian method of 

 prepiring fine hard Para, the author proceeds to the 

 subject of smoked rubber and smoking houses. The mf>st 

 important precaution in any smoke house is to maintain the 

 temperature below a maximum of about 110° F., since if 

 the rubber is dried at a higher temperature, tackiness occurs 

 and the rubber deteriorates. A thermometer — preferably 

 a maximum and minimum thermometer — should be used irv 

 all smoking houses, and should be hung about midway up- 

 the height of one of the racks on which the rubber is suspend- 

 ed. Another point to remember is that the rubber should be- 

 placed in the smoke house while still wet. Prolonged 

 smoking does not appear to alter the rubber. One further 

 advantage of smoking is the rapidity with which the rubber 

 dries, so that much smaller storing room is needed on estate* 

 where smoking is carried out. Moreover, if desired, the 

 rubber can be sent to the market in about a fortnight, op 

 even after the elapse of a shorter period. 



Two problems which will receive further investigation 

 are the artificial smoking of rubber by the employment of 

 creosote with the coagulant, and the question of the useful- 

 ness of vacuum driers. No conclusive results have so far 

 been obtained in the Federated Malay Stales. 



1 )ealing next with rubber machinery, it is pointed out 

 that if two rubbers have been prepared in the same way, and 

 one converted into 'crepe' and the other into sheet, the latter 

 will be found to possess superior physical qualities to the- 

 former. This is j-ecogni/.ed by manufacturers. Rollers for 

 'crepe', running at differential s|ieed3 like 3 to 1 are depre- 

 cated as being unnecessary and injurious. 



Alluding again to the important matter of collecting; 

 cups, it is emphasized that the beat kind to use is the- 

 porcelain or glass semi- spherical shaped one recently 

 introduced to the market. This kind can be easily cleaned and 

 kept clean, and although the liability to fracture has until 

 lately been an objection to the employment of glass the recent 

 introduction of better annealed glass renders the objection 

 invalid. The succeeding section in the Bulletin concerns the 

 acidity of raw rubber In general, smoked rubbers contain 

 the largest quantity of acid, sheet rubbers (unsmoked) being 

 second, whilst crepe rubbers contain the snullest amount. 

 Therefore fine hard Para contains more residual acid than 

 plantation, and it absorbs it from the smoke in curing.^ 

 This fact is not always recognized. In the case of plantation 

 rubber, the acid is, to a large extent, eliminated by the- 

 washing process. 



After describing, in connexion with the density of latex,, 

 a useful form of hydrometer graduated in such a way that 

 a difference of OOIG is ranged over a stem of 3 to 4 inches in 

 length, the author concludes with a large number of viscosity 

 figures from which the general conclusion is drawn that with 

 rubber from one species of tree there is a distinct relation 

 between the viscosity curves and the ph>sical (juality of the 

 rubber, and it is considered likely that the test may become 

 11 valuable control in the laboratory though not of much use- 

 on estates, sinie slight HuctuatiinF in temj-eralure lead to 

 variations in the results obtained. 



