188 



The Supplement to the Tropical Agriculturist 



the trees having travelled about 800 miles by 

 rail and from 3,000 to 4,000 miles on the deck 

 of a steamship, they arrived in excellent con- 

 dition ; for no sooner had the tapping knife 

 made the necessary V-shaped incisions than 

 the latex flowed freely. The latex so obtained 

 was afterwards coagulated in a centrifugal 

 machine. — H. & C. Mail, July 7. 



At the conference, which was continued on 

 6th inst., at the Rubber Exhibition, under the 

 presidency of Dr. Torrey, the first paper read 

 was a highly technical essay by Professor 

 Schideowitz on 



" VISCOSITY OF RUBBER SOLUTIONS." 



He said he had studied for two years the 

 effect of various factors on viscosity, the effect 

 of heating in solution, which did not always 

 cause disaggregation. On the contrary, in the 

 case of old forest tree rubber the aggregation 

 appeared to increase. In the case of young or 

 immature trees also it appeared to decrease. 

 Then he studied the effect of deresination, 

 and here again it was found that in the case 

 of old forest trees the result was positive — that 

 was, that the viscosity increased. Then he 

 studied the effect of the method of coagulation 

 on a number of samples, and found, as he ex- 

 pected, that he got very high variations by the 

 viscosity method. 



A long discussion followed, the most popular 

 point raised being whether these tests would 

 be useful to the planter on the estate. Pro- 

 fessor Schidrowitz said that where the planter 

 was in a position to carry out viscosity tests 

 on scientific lines, it might be useful to him 

 in controlling the quality of his rubber. But he 

 wished it clearly to be understood that he did 

 not prefer the viscosity method to the vulcanisa- 

 tion method. The vulcanisation method was 

 preferable where it could be applied, but the 

 viscosity method was useful where it could not. 



Dr. Huber then react a paper on the 



RUBBER TREES AND WILD RUBBER RESERVES 

 OF THE AMAZON. 



He admitted that interest in the subject was 

 rather discounted by the greater popularity of 

 middle red rubber ; but he thought it would in- 

 terest people to know something about the 

 region which yielded the best kind of wild rub- 

 ber. He went into the history of wild rubber 

 at length, and dealt with the variations of the 

 various kinds of rubber which had been found 

 in the different parts of the country. Hevea 

 contained some well-defined groups of species 

 which, though in the first line of practical value, 

 were characterised by botanical sub-divisions. 

 By far the greater part of para rubber came 

 from Hevea Brasiliensis, which was not only the 

 best, but the most unknown variety. It grew 

 throughout the whole Amazonian basin, prin- 

 cipally in its southern part, where it occupied 

 not only the low alluvial lands of most of the 

 affluents of the Amazon, but some of the higher 

 lands, principally between the River Tapajoz 

 and Madera, and also between the higher course 

 of this river and the upper River Purus 

 aod its tributaries, and the Acre and others. It 

 was, however, possible that the trees of the 

 higher land were of a very near but distinct; 

 Jsiad ot Hevea, It was evident, however, that 



the seeds obtained by Mr Wickham, who went 

 to the East, were of the true Hevea Brasiliensis. 

 There were particular kinds of Hevea on the 

 Rio Negro whose latex was said to produce good 

 rubber ; but on the whole, little was known of 

 the rubber yield of these trees. Of the 12 species 

 of sapium, only one was recognised as producing 

 good rubber. These trees were of rapid growth 

 and the latex was often mixed with Hevea. 



The exploitation, however, of these trees was 

 not popular, owing to tapping difficulties. The 

 production of a more suitable tapping knife 

 might lead to its becoming more popular. 

 Very important as a future reserve of wild 

 rubber was the Caoutchouc tree, which was 

 the large virgin tree of the forest, and was 

 rich in caoutchouc. There was an enormous 

 reserve here. The export of caoutchouc had 

 increased from 349 tons to 8,000 tons. So many 

 trees were there that the natives did not trouble 

 to tap the trees in the ordinary way, but cut 

 down the tree bodily. He advocated the making 

 by the Government of "forest reserves" in order 

 to protect these important trees from extinction 

 in this way, because there was undoubtedly a 

 large and valuable reserve here. 



Mr. Clayton Beadle, in the next paper, called 

 attention to a new method of 



TESTING RUBBER BY USING THE ENERGY OF A 

 FALLING PENDULUM 



and noting the distance of the height to 

 which the pendulum rises before and after 

 breaking the specimen, and utilising that in 

 recording the actual amount of work done in 

 breaking the specimen. They did not at present 

 know the-value of this. In the Schwartz machine 

 many thousands of determinations had to be 

 made of mixtures of known composition before 

 the result could be properly interpreted. In 

 this case the machine would have to be used 

 on mixtures of known composition, and made 

 under known conditions before they knew the 

 value to be placed on the results and how they 

 were to interpret the figures. 



In the afternoon a meeting was held of the 

 India Rubber Testing. Committee, Dr. A. H. 

 Berkhout, who presided, said that at the 

 meeting held three years ago he was asked to 

 take the initiative in forming this company. The 

 committee had been formed, and had sections in 

 various countries, at the head being Mr Herbert 

 Wright, in London ; Professor Dr. Warburg, 

 Berlin ; M Pierre Breuil, Paris ; Mr O PearsoD, 

 New York; Dr. Herbert, Vienna; Mr Kelway 

 Bamber, Ceylon; and M J E Fol, Delft. First, 

 they had to conquer the difficulty of establishing 

 standardising methods. Of course, it was neces- 

 sary they should understand each other in re- 

 gard to the physical and chemical proceedings 

 of testing indiarubber. It was too bad that a man 

 should not know the signification of his own 

 figures, and not be able to understand someone 

 else's. What they wanted was auniform standard 

 for testing rubber. This standard should be 

 beneficial to rubber manufacturing and the culti- 

 vation of rubber. 



The secretaries of the various national bran- 

 ches then reported on the bteps taken in their 

 respective countries to start the work of the 

 association. 



