25 



other some 3^ miles distant, in the middle of the rubber plantation. 

 In the future an electric tram system will be laid out to facilitate 

 transportation on the estate. The new Pan-American railroad 

 passes within a few miles of the plantation buildings, and La Za- 

 cualpa station will mark the place of communication w ith the outer 

 world. 



The Preparation of Rubber, 



At present the rubber factory is in temporary quarters under 

 the roof of the estate saw-mill. A proper factory building will be 

 erected next year. Briefly stated, the system of preparing rubber, 

 which will then be adopted, is as follows : — The latex brought in 

 from the field is emptied into a collecting tank, where an equal 

 amount of water is added. Inside this tank is an endless screw 

 which slowly revolves and thus mixes the latex and the water 

 without causing a separation of the natural clumps of globules. 

 In case the preparation has to be postponed, a small amount of 

 dilute formalin is slowly added from an automatic drip can. From 

 the collecting tank the latex passes through a strainer into a 

 stirring vat, where more water is added and the mixture is well 

 stirred ; the temperature being slightly raised with steam passing 

 through pipe coils inside the vat. 



If we adopt a smoking or fumigating process, which is not yet 

 definitely decided, the latex would next pass into a zinc cylinder 

 and through a series of sieves between which the fumes are 

 pressed. The thoroughly fumigated latex falls into a vessel, 

 whence it is run off, fifteen minutes later, into settling tanks. Here 

 the creaming of the latex' takes place, and by very gentle stirring 

 of the top layer of " cream " coagulation is assisted. Sometimes 

 a coagulant has to be added, but more often the latex shows a 

 tendency to coagulate too rapidly. From time to time some of the 

 mother liquid, which is dark brown, resembling beer, is drawn off 

 from below and clean water is slowly added. 



The coagulated rubber slabs are passed on to the washing 

 machine, and after a thorough washing, the rubber is dried in vacuo. 



It is very difficult, even by adding coagulants, to effect 

 the coagulation of all the rubber in the latex. As an adjunct to 

 the creaming process all of the remaining latex, after two cream- 

 ings, is passed through a centrifugal separator, and after this the 

 mother liquid does not contain any more rubber. 



All the rubber is pressed into blocks in a strong screw press 

 after drying. Two years ago Mr. Harrison prepared with tartaric 

 acid on La Zacualpa a big rubber block as an experiment, and it 

 proved to be the most attractive and practical way in which we can 

 ship the clean plantation Castilla. I have received the advice from 

 English rubber brokers to send Castilla rubber as crepe, but I 

 greatly doubt the advisability of this, as the oxidation would be 

 considerable, and Castilla suffers more from this than Para rubber. 



Sulphurizing the Latex. 



The addition of finely pulverized sulphur by a process corres- 

 ponding to the vulcanization suggested itself, in the early stages 

 of my experiments with Castilla latex in the laboratory at La 



