284 INDUSTRLVL PLANTS 



with caoutchouc is called vulcanization. By using much 

 sulphur and a high degree of heat hard rubber or vulcanite 

 is produced. 



The discovery of vulcanization revolutionized the rubber 

 industry. Not only were the old uses greatly extended but 

 new uses for rul)bcr have so multiplied that caoutcliouc now 

 ranks among the most important ]iro(lucts of the vegetable 

 kingdom. The elasticity of soft vulcanized rubber makes it 

 invalualile in various articles of dress, for many surgical 

 purposes, foi' elastic bands, solid or pneumatic tires, for 

 various parts of machines, and for rubber balls, toys, and in- 

 numeraltle other articles of minor us(>. Its imperviousuess 

 to water and air, combined with its Hexibility, render it of 

 greatest service for wateriir(jof garments or coverings, sub- 

 marine diving-dresses, Mexil)le tubes or hose, water-bottles, 

 air-cushions, life-preservers, por-table boats, etc. Hard rub- 

 ber takes a high jiolish and is very resistant to the action 

 of acids and other corrosive fluids. Therefore it makes the 

 best possible material for ])hotographer's developing trays, 

 certain parts of fountains i^ens, tele])hones, surgical instru- 

 ments, etc., while it is a most excellent and inexpensive sub- 

 stitute for horn or shell in such articles as combs and handles. 

 Both vulcanite and the softer vulcanized i-ubber are exten- 

 sively used for insulation in electric work. Pui'e I'ubber on 

 account of its I'cmarkable adhesiveness is an indispensable 

 part of the l)est surgeon's plaster, and of the rubber tape 

 used in repairing bicycle tires and in electric wiring. The 

 curious erasing power of rul^ber, whetlier ])ure or \'ulcanized, 

 is possessed by no other substance to anything like the same 

 degree; hence one <.)f its earliest uses still remains <ine of the 

 commonest and most important. 



Caoutchouc as a raw material bears, as wi' ha\(- S(>(m, some- 

 what the same relation to the milk>' juice of plants that 

 cheese bears to the mil]< oF animals. That is to say, it sepa- 

 rates from the fluid part as curd from whe>', and liecomes 

 solid by drying. C'hemicalh', however, caoutchouc is tiuite 

 different from the jiroteid of which (diee.se mainly consists. 

 Pure caoutchouc is a hiiflrdcarhoii: in other words, it contains 

 only hydrogen and carbon in its composition. Commonly 



