88 MOZAMBIQUE 



Coagulation may take place almost at once, or 

 after some hours. Calcium chloride is now 

 coming into use as a coagulant, mixed in the 

 proportion of 100 grammes to 1 litre of water, 

 each man being given 8 litres of the mixture 

 daily. The best method of collecting the rubber 

 is by rolling it on a stick or small roller. In 

 this way both hands can be used and the rubber 

 pulled away from the trunk to avoid any bark 

 getting in. The method of treatment afterwards 

 varies. In some cases the rubber is sliced and 

 soaked in water for a few hours to get the smell 

 of the acid out, and then laid out on tressellated 

 shelves in the shade to harden. In others it is put 

 through a washing-machine and rolled into sheets. 



The process adopted will depend upon ex- 

 perience, it being always remembered that clean 

 tough rubber is what the manufacturers require ; 

 and that while washing or a special treatment 

 may procure a slight increase in price, it may 

 be at the expense of more than a corresponding 

 increase in the labour bill. 



Peeling off the outer bark before tapping is 

 sometimes practised. In old trees the bark is 

 tough and difficult to pierce with a knife, and 

 the dry scales are apt to get into the rubber. 

 It takes three times as long to bark a tree as 

 to tap it, and though a tree is barked only once 



