RUBBER MANUFACTURE. 119 



An improved type of a hydraulic block press, specially 

 designed and manufactured by Messrs Francis Shaw & Co., for 

 compressing rubber into blocks for shipment, is shown, Fig. 23. 



This is a twin press having two boxes worked from a single 

 pump, the power for working and the presses being entirely self- 

 contained. The pump is fitted on the stand, which forms a tank 

 containing the water, by means of which the presses are worked. 

 The total pressure obtained is about 12 to 15 tons on each ram. 



In addition to expediting the work of the estate a minimum 

 surface of the rubber is exposed to deleterious atmospheric 

 influences, and where freight is charged on cubical capacity an 

 appreciable economy is effected. 



SCRAP RUBBER. 



The latex which flows over on the bark from the tapping 

 channels, and that which exudes from the incisions, but fails to 

 reach the collecting vessels, usually coagulates in a few hours, 

 and is picked off by hand. That which adheres to the collect- 

 ing cups, pails, &c., should also be collected. This forms what 

 is known as scrap rubber. After being thoroughly washed, 

 and mechanical impurities separated, it may be placed on the 

 market in this condition, or be passed through the washing 

 machine immediately after collection, and turned into crepe 

 rubber. 



The parings of bark from the tapping incisions should be 

 likewise collected and passed through the same machine which 

 macerates the bark and extracts the particles of rubber therein. 

 This process is considerably facilitated by soaking the bark 

 parings in water for several days previous to passing them 

 through the machine, and by the use of caustic chemicals. 

 These forms of rubber are improved by being smoked over a 

 wood fire. 



