46 1 



which results in the production of crepe rubber. Although it 

 present neither clean biscuit, sheet, worm, nor crepe rubber need 

 be washed for ordinary use, yet if washing and sheeting plantation 

 rubber is to be dispensed with in the manufactory, it would be a 

 great advantage when dealing with the larger quantities to have it 

 ready in the washed and sheeted form, and the advantage of crepe 

 over other forms would be most marked when dealing with manv 

 tons at a time. b 



ADULTERATION OF WASHED RUBBER. 



8. 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 would reveal the 

 sophistication. In unprincipled and fraudulent hands such adul- 

 teration 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 pro- 

 duced. 



ANALYSIS OF RUBBER. 



9 The chemical composition of rubber has no consideration 

 either from the buyers or the manufacturers— the former base 

 their valuation entirely upon the appearance, feel, smell, and ap- 

 parent 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 systematically 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 wash- 

 ing — 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 with which varia- 

 tions in their amounts in the raw material are regarded is natural 

 and quite intelligible. 



PACKING. 



io. There are several points which must be remembered in 

 packing rubber. Rubber at temperatures above 65°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 

 the ageing of the rubber. Dust and grit which find way inside the 

 cases adhere to the rubber. The care requisite in packing, there- 

 fore, depends upon the form in which the rubber is shipped. If 



