Gums, Resins, 



358 



reputation. That it should be free from any trace of softening or stickiness is 

 still more important ; rubber which is " tacky " in the slightest degree cannot 

 be relied upon in practical use. Unfortunately there has been a considerable 

 amount of rubber showing this defect of softness with a sticky and tacky surface, 

 produced on plantations, and these samples have tended to injure materially 

 the reputation of plantation rubber." 



The manufacturers' views regarding the form the raw rubber should come 

 to market were not similarly prejudiced, and they would be glad of anything, 

 in large enough quantities, as long as the rubber is " evidently dry and clear enough 

 to show by inspection the absence of any mechanical impurity." 



Since Mr. Burgess's visit sheet rubber, chiefly from Lowlands estate, has 

 come to the fore, and he is candid about an important drawback to crepe : — 



" There is one danger connected with the use of a washing machine on a 

 plantation. By its means adulteration with inferior rubber, rubber substitutes, 

 and recovered rubber, could be carried out without possible detection by eye 

 or hand inspection, although chemical analysis or practical use of the rubber 

 Avould reveal the sophistication. In unprincipled and fraudulent hands such 

 adulteration might be carried to a considerable pitch before detection occurred, 

 and this possibility of misuse should not be lost sight of by those who are responsible 

 for the purity of the rubber produced." 



THE CHEMICAL COMPOSITION OF RUBBER, 



Mr. Burgess found, says the " Times of Ceylon," had no consideration either from 

 the buyers or the manufacturers — the former base their valuation entirely upon the 

 appearance, feel, smell, and apparent strength of the rubber when pulled about in 

 their hands, the latter rely chiefly upon the way the rubber works upon their machines 

 during manufacture, though in a few instances properly controlled and systemati- 

 cally carried out tests of tensile strength and elasticity are made with samples 

 of the rubber prepared and vulcanised. The percentage amount of the impurity 

 which is inherent in the rubber, and which cannot be removed by washing— 

 that is, the oily, resinous and nitrogenous, or proteid, impurity— is practically 

 never determined in the factory, and a statement of these values with the 

 rubber for sale would neither be understood nor attended to. In the present 

 state of ignorance as to the influence of these ingredients upon the working 

 qualities of the rubber during manufacture, the apathy Avith which variations 

 in their amounts in the raw material are regarded is natural and quite 

 intelligible. 



HINTS ON PACKING. 



" There are several points which must be remembered in packing rubber. 

 Rubber at temperatures above 65 degs. F. is naturally adhesive, and clean surfaces 

 pressed into contact tend to stick to one another, though the rubber be dry 

 and show no vestige of tackiness. Rubber during transit invariably shrinks in 

 bulk owing chiefly to the action of its own weight in compacting the mass, 

 and partly perhaps to a natural shrinkage of the rubber substance with ageing 

 of rubber. Dust and grit, which find their way inside the cases, adhere to the 

 rubber. The care requisite in packing, therefore, depends upon the form in 

 which the rubber is shipped. If in clean washed crepe, which it is hoped will 

 be vised without further washing and sheeting, every care should be taken to 

 prevent the layers adhering to one another, and to avoid the use of any pack- 

 ing material which can make a dust out of itself, or which will admit dust 

 and dirt from outside. This can be effected by the use of clean, well-made, 

 and fitted cases, which should not contain more than 80-100 lbs. of rubber, and 

 which might with advantage be partitioned to prevent the whole of the rubber 



