PARA RUBBER. 107 



fi eneral Characters. 



The behaviour of the latex, when subjected to physical and chem- 

 ical agencies, may here be touched upon. It readily mixes with 

 water without creaming. Parkin kept some latex diluted four times 

 in an ice chamber for days without showing any signs of creaming. 

 It is very difficult to separate the caoutchouc by centrifugal force, 

 and on several occasions a speed of over 10,000 revolutions per min- 

 ute did not effect a separation of the caoutchouc of normal latex. The 

 effect of freezing was tried by Parkin, a mixture of ice and common 

 salt being used to give the low temperature ; after thawing, the latex 

 appeared to be the same as before, and creaming was not hastened 

 by the changes of temperature. Addition of ammonia or formalin 

 prevents or delays coagulation, the former by neutralizing the acids 

 as soon as they are formed, and the latter by acting as an antiseptic 

 and preventing the decomposition of the proteid matter. Acids 

 bring about coagulation in the cold, but the action is much quicker 

 when wanned. The latex may, however, if diluted, be boiled and 

 yet coagulation is not brought about. 



These points should be borne in mind by the planter who is in- 

 clined to experiment mechanically and chemically with the object 

 of extracting the undesirable substances usually present in latex. 



