IO8 PARA RUBBER. 



Consequently vulcanite vessels would probably prove more 

 satisfactory. 



It is important that the curing-house be kept clean. It 

 should not be situated near any works which create dust ; in 

 fact it is necessary to treat a rubber curing-house in an exactly 

 similar manner with regard to cleanliness as a dairy. 



Within twenty-four hours the rubber particles will have 

 coagulated, and risen to the surface in the form of a thick curd. 

 Immediately this occurs the coagulum should be lifted out, 

 thoroughly washed, and then pressed between heavy rollers to 

 force out any liquid which may have been imprisoned inside 

 the mass. To effect this a machine similar to a laundry mangle 

 is recommended. This process needs very careful attention, as 

 the stench common to many rubbers is due to putrescent 

 moisture shut up in this way, and it naturally has in time a 

 deteriorating effect upon the product. After pressing, the rubber 

 discs should be placed on a clean porous surface to drain, and 

 then placed in the smoke of a wood fire for at least a day. 

 Afterwards they should be spread singly on shelves made of 

 canvas, rattan, or some similar material which will permit a free 

 passage of air through. 



The shelves of a tea-withering house answer admirably ; the 

 illustration (Fig. 17) depicts one employed for this purpose in 

 Ceylon. Artificial heat is not absolutely essential, but hastens 

 the drying process. 



On no account must the rubber be exposed to the sun, as 

 this produces a permanent stickiness, which considerably de- 

 preciates its value. 



Drying should be continued until all opaque blotches, which 

 are due to moisture, have vanished, and the rubber is translucent 

 and of a uniform colour all over. 



The weight of dry rubber obtained from a given quantity 

 of latex is approximately in the proportion i to 2, i.e., i Ib. of 

 latex will yield about \ Ib. of dry rubber. 



All tapping instruments, collecting cups, coagulating pans, 

 &c., should be thoroughly washed after use and kept clean. 



A chemical analysis of Para rubber prepared in this manner 

 from ten-year-old trees growing in the Botanic Gardens, Gold 

 Coast, gave the following results : 



