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native-prepared product of the Para rubber tree the best of all grades 

 of rubber, but as the method is not only very expensive and exceed- 

 ingly tedious, but also harmful to the health of the operators, the 

 inventor of the Da Costa coagulating plant thought of devising a 

 means of doing mechanically all that is now done by hand in the 

 rubber forests of Brazil. This plant, which is the result of practical 

 experiments and tests by Mr. Da Costa, and is made by Messrs. David 

 Bridge & Co., the well-known Rubber Engineers of Castleton, Man- 

 chester, needs no chemicals whatsoever, so long as tropical forest woods 

 are available for heating the boiler, as well as green foliage of palms 

 for generating smoke in the boiler furnace. 



The coagulating and smoking by means of this plant is the simplest 

 of all operations in the rubber industry, and may be performed by any 

 inexperienced hand, the process being as follows : — 



The latex, being brought from the field, is strained if it is found to 

 contain mechanical impurities, and then poured into the coagulating 

 tanks. Steam is meanwhile being raised to about 30 to 35 lb. in the 

 boiler, forest woods alone being used for fuel. On to the burning wood 

 in the furnace are then thrown green palm leaves, nuts, or any green 

 twigs of tropical trees, the distillation of which produce acetic acid, 

 whilst the fumes of the green foliage would be found to contain creosote 

 to some extent. These fumes are accumulated in a special receptacle 

 after being cleared of cinders, &c. and are then forced into the coagu- 

 lating tanks by a steam injector. 



The force of the steam violently agitates the latex, and during this 

 operation every particle of it is reached by the smoke. In about ten 

 minutes or rather more if the quantities to be dealt with are very 

 large, caoutchone globules coagulate and separate from the lyes and 

 rise in the surface, 



The coagulate substance, after being allowed to cool off in the 

 tanks, is afterwards taken to a small press and turned out in the shape 

 of flat block rubber. These, in their turn, are then re-blocked into club 

 form, and after being dried, either in a stove or vacuum, are ready for 

 shipment. If the flat blocks are only lightly compressed into the 

 form of cubes, whilst still being sufficiently air-tight in the centre to 

 prevent discoloration setting in, they can be easily torn asunder by the 

 manufacturers and used in their machines, without the extra labour of 

 previously cutting them into convenient sizes. 



Rubber prepared in this way retains all the native elements, as 

 regards resiliency and tensile strength, of fine hard native Para, and 

 will last as long as the wild rubber— if kept in a crude state, for years. 



It is claimed for this coagulating plant, therefore, that it not only 

 has the advantages of dispensing with the assistance of chemical agents 

 in a liquid form but also allows the producer to send to the market 

 the only preparation that satisfies all the rubber manufacturers' require- 

 ments at the various mannfacturing centres throughout the world. 

 In addition to this, the inventor claims that it also possesses the 

 unique property of being the only apparatus which can convert the 

 latex of the Castilloa elasteca into a rubber of equal market value, 

 appearance, and colour, to that of the best Para sort exported from 

 Brazil.— Tropical Life. 



