382 



The Supplement to the Tropical Agriculturist 



dents have to use their hands and work hard. A 

 great deal of their time is spent in the field 

 where they learn the handling of implements, 

 livestock, &c. The fees paid are noi high, but 

 this is compensated for by the actual work put 

 in by the students. 



There is a Government institution here known 

 as the 



LAND BANK FOR PROVIDING LOANS TO FARMERS, 



for the improvement of their farms. 1 believe it 

 originated in the time of Sir Henry McCallum, 

 but am not sure. I wish your Governor's 

 schemes for agricultural education, &c, all 

 success, I hope the native cultivator has of late 

 imbibed some progressive ideas since I knew 

 him. Otherwise it will be hard and slow work. 



THE NEW RUBBER COAGULANT. 



Of Mr. Aubrey Elias. 

 In our issue of August 20 we published some 

 particulars of a chemical reagent which will, 

 according to the claim made by the discoverer 

 of the process, Mr O Aubrey Elias, F.C.S., 

 quickly and effectually coagulate rubber milk 

 without imparting any deleterious effect to the 

 finished product. In support of Mr Elias 's 

 claim, Mr C T Gardner, dispenser at the Miller 

 General Hospital, Greenwich, has given to the 

 public the result of his analysis of specimens of 

 rubber treated under the new process, Mr 

 Gardner has also given particulars to a repre- 

 sentative of the Press Association, and these 

 were recently set forth in the Financial Times. 

 It is the 



SCIENTIFIC ASPECT OF THE DISCOVERY 



which most appeals to Mr Gardner, and in 

 dealing with the invention from that point of 

 view he said the standard of rubber qualities 

 was tine Para hard cured, which consisted 

 principally of caoutchouc, a substance bearing 

 the chemical empirical formula (010 Hl6)n, 

 with about 1"3 per cent, of resin, a little water 

 — say, about - 75 per cent. — from 3 to 

 4 per cent, of proteid, and yielding from 

 0'2 to 1 per cent, of ash. There was also 

 colouring matter present and sometimes 

 foreign impurities. Inferior rubbers might 

 contain as low as 50 per cent, of caoutchouc. 

 The presence of proteid matter in the latex 

 ' might be shown by a very pretty test known as 

 the xanthoproteic reaction. In this test nitric 

 acid was added to the latex and the liquid was 

 boiled, when it turned yellow, the change in co- 

 lour being due to the formation of xanthoproteic 

 acid. Ammonia added to the fluid caused it to 

 become a rich orange. Rubber containing pro- 

 teid, when diffused in chloroform, left an in- 

 soluble coagulum varying in amount with the 

 quantity present ; in other words, the proteids 

 were nondiffusable. Those proteids were highly 

 complex bodies which in the tree were built ud 

 from the simple chemical compounds acting as 

 nutritive material to the tree. The particular 

 kind of proteid in the latices of rubber-pro- 

 ducing plants was an albumen coagulable by 

 heat at 70 degrees. The coagulant invented 

 by Mr Elias seemed to practically, if not 

 altogether, eliminate the undesirable pro- 

 teid. " For this reason," added Mr Gard- 

 ner, " I believe this coagulant will produce 



A REVOLUTIONARY EFFECT ON THE RUBBER 

 WORLD." 



The processes of coagulation could not be 

 regarded as strictly scientific, Mr Gardner says, 

 and, indeed, a great deal of waste often took 

 place, with the frequent result that rubber was 

 produced lacking the resiliency or even, at times, 

 avoidable impurity. One advantage of the new 

 coagulant was that no technical skill was re- 

 quired to use it. Its use, he believed, would 

 result in an enormous saving of time and mate- 

 rial. Its ready facility of transport would render 

 it of great commercial value. Acetic acid and 

 other forms of coagulants at present in use were 

 very inconvenient to transfer across country in 

 comparison with the new method, which was in 

 powder form, and could be carried in a glass 

 tube. Another point was that of a little of the 

 powder or coagulant, added to the milk, effected 

 complete coagulation in the space of a few 

 minutes, and in bulk the action was almost as 

 quick. At present acetic acid took from eight 

 to twenty-four hours to produce the same result. 

 With this latter process, too, there was the 

 danger that the use of insufficient acid would 

 produce incomplete coagulation, and if too much 

 were employed it would redissolve the proteids 

 and retain them in the substance. The new 

 method would also prove of value from the point 

 of view of health saving. It was impossible Co 

 remove the latex any distance for even shaking 

 in such climates would cause it to partially 

 coagulate. The process, in any event, therefore, 

 had to be conducted on the spot, and there was 

 serious impairment to health among the native 

 labourers who, at present, were obliged to re- 

 main in unhealthy marshy districts, whilst 

 awaiting coagulation. The Elias coagulant, he 

 believed, would be found to decrease the quan- 

 tity of resin in the rubber, if it were care- 

 fully used, with the result that it would 

 vulcanise much better ; it would also tend to 

 act as a preservative. Some of the powder 

 had already been sent to Peru, the Congo, 

 and other rubber-producing countries, and the 

 samples he analysed were sent to him by a 

 South American company which had adopted 

 the new process.— H. & C. Mail, Sept. 10. 



A NEW METHOD OF COAGULATING 

 RUBBER LATEX. 



A PRACTICAL DEMONSTRATION WITH 

 "PURUB." 

 Invention of a German Expert. 



Simplicity in the preparation of the latex 

 of tho rubber tree into rubber itself for 

 manufacturing purposes is a matter of the 

 greatest importance to rubber planters and 

 manufacturers. In Ceylon at present, as in 

 most other parts of the world where rubber 

 is grown, the most commonly used chem- 

 ical for coagulating the latex is acetic 

 acid. It is most important in treating 

 latex that the natural moisture in it should be 

 preserved and the one great disadvantage of 

 using acetic acid is that after the latex has 

 coagulated the rubber must be thoroughly 

 dried before it can be lit for shipping which 



