252 



Smoking and Coagulation. — "The coagulation of the latex may 

 be hastened by exposing it to heat and the products of combustion 

 of a fire. The latex can be coagulated fractionally by such a 

 process, and the finished product, when properly manufactured, is 

 less liable to putrefaction than the rubber prepared by many other 

 methods. The smoke from burning palm nuts used in the Amazon 

 district, contains, among other substances, small quantities of 

 acetic acid, acetone, and creosote, The acetic acid is probably the 

 agent responsible for effecting the coagulation ; the other sub- 

 stances, particularly the creosote, are absorbed, the latter acting as 

 an antiseptic in preventing the rapid decomposition of the albu- 

 minoids present. In Brazil the latex is poured into a shallow 

 basin 6o cm. to I metre in diameter and 20 to 30 cm. deep, and 

 pieces of bark, dirt, &c., removed. A fire is then made of wood 

 and resinous substances, and is kept going either with green 

 branches of Miinusops data, or with palm nuts from Attalea excclsa, 

 and Maximiliana rcgia, these palms are usually grown in the Botanic 

 Gardens in various parts of the tropics, the latter species being 

 more commonly known as the " Cocurito " palm. A chatty, open 

 at both ends, is placed on the fire and the smoke allowed to issue 

 from the upper aperture. A paddle like implement is then dipped 

 into or covered with the latex, and held over the smoke until the 

 latter is coagulated. It is stated by Bonnechaux* that 8 litres of 

 latex are completely coagulated in about li hours by these means. 



"The decomposition of the albuminous substances in the 

 rubber may be prevented by the addition of suitable antiseptic 

 reagents to the latex, when the rubber is prepared in other ways, 

 though quickness in drying or complete extraction of the moisture 

 from coagulated rubber is often sufficient to bring about the same 

 result. Dickson's apparatus is devised to meet many of these 

 requirements." — (Herbert Wright.) 



"Samples of rubber prepared at Kuala Kangsar have been 

 reported on as equal to good Para (Brazilian) and would fetch 

 best Para prices. I have always found the latex to coagulate 

 readily with only the addition of a pinch of alum, and by placing 

 immediately in smoke, both putrefaction and mould are avoided. 

 If the rubber is sound, the market value depends on the state of 



dryness in which it is received. What has been prepared at 

 Kuala K angsar has been kept smoked until shipped. A parcel 

 sent to London 3j years ago was reported to have lost 26i per 

 cent, in washing, and the manufacturers thought that if sent 

 home in bulk, the loss would reach 30 per cent. This, however, is 

 a question for the planter himself ; smoke has a chemical action 

 in the coagulation of latex from Hevea as well as saving decom- 

 position, and assists in gradually drying. To be as dry as possible 

 depends on the time the rubber has been kept smoked, and I am 

 of opinion that dry marketable rubber could not be prepared 



under two months." — (R. Derry, Singapore). 



* Jumelle. 



