PARA RUBBER. 



1 35 



when chemical anion takes place between the components, and vul- 

 canized rubber is formed. The whole of the sulphur does not corn- 

 hint- with the indiarubber, but if the high temperature is maintained 

 for a long period, more and mote of the free sulphur enters into com- 

 bination and produces a darker and tougher vulcanized product. 

 Though most of the rubbei is vulcanized by the above process, 

 the cold cure, dependent upon the action of sulphur components in 

 the cold, is often adopted. In the cold care, dilated sulphur 

 monochloride is mixed with the rubber, with which it readily 

 combines at ordinary temperatures, and produces a. vulcanized 

 product suitable for the manufacture of goods which would be 

 damaged by hi<j;h temperatures. Sulphur monochloride is a liquid 

 ;ii ordinary temperatures, and on account of its violent action with 

 indiarubber is diluted by dissolving in carbon bisulphide before 

 being used for vulcanizing. 



Quantity of Indiarubber in Common Article 

 The important part which indiarubber and sulphur, 



with other substances, play in the manufacture of articles in 



use, is little less than remarkable. 



The following analyses are given by Weber : - 



tOget her 



common 



l 



Roller 



( \<\ ering. 



per cent . 



. 24-49 



Steam 



per cenl . 

 12-73 

 •_'• 10 



3 



( >uter Covei 



of .i I j re. 



per «-.-iii . 



54-70 



0-88 



4 

 Tobacco 



P sh. 



per cent. 



50 1-1 



0-27 



19-53 



37-2] 

 2-50 



< larden 

 Hose. 



percent. 

 ;i 29 



1 83 



2 I i 

 26-28 



7-34 



28-90 

 2-20 



Indiarubber 

 ulphur 

 Sulphur of vulcani- 

 zation .. 0-84 1-99 

 Mineral matter .. 72-33 62-81 41-08 

 Organic extract .. L - 10 2-82 1-34 

 Carbonaceous matter 

 Fatty subst itute 

 Chlorine in rubber . . 



The presence of as much as 50 to 54 per cent, of indiarubber 

 in an ordinary tyre and tobacco pouch, the use of nearly 30 per 

 cent, of fatty substitutes in garden hoses, and over 7<> percent, of 

 mineral matter in roller covering made from fine Para, should be 

 noted. 



The uses of Para rubber have been greatly augmented in recent 

 years by the increased production of automobiles and accessories, 

 and it is difficult to accurately forecast what the demand for rubber 

 will be when it is adopted for wheeled traffic and public pass 

 vehicles generally in many parts of the world. It has also been 

 largely used in recent times in the making of pavements, balls 

 boots, articles of clothing, instruments, belting, &c, and "solution." 

 Plantation rubber is preferred by many manufacturers for 

 "solutions," on account of their being able to use it direct with 

 the solvents without purification. 



