January 1, 1916.] 



THE INDIA RUBBER WORLD 



201 



CEYLON AND MALAYA CROP PERCENTAGES AND 

 RAINFALL. 



■ I 'HE Rubber Growers' Association, Loiuloii, England, has 

 ■*• issued two comprehensive charts and statements show- 

 ing the percentages of crop harvested, and of rainfall recorded 

 monthly by representative estates in Ceylon and Malaya. 

 The figures are computed on annual crops of from 17 to 20 

 million pounds of Malaya rubber, and from five to seven 

 million pounds of Ceylon rubber. 



It appears from these charts that the wintering period, 

 which occurs in February and March, coincident with the 

 lowest rainfall, has a much greater effect on the crop of rubber 

 in Ceylon than in Malaya; but the figures are no doubt 



' P£RC£MrA6C3 



LIOhTUHE 'KAINFALL P£K£NrA6£5 



Chart Showing the Percentage of Crop Harvested, and of 

 Rainfall Recorded Monthly in 1913 and 1914 by Repre- 

 sentative EsT.\TES IN Malaya and Ceylon. 



aflfected by the practice on some Ceylon estates of ceasing 

 or reducing tapping operations during the wintering season. 

 The variation in the daily distribution of rainfall in the re- 

 spective countries and in the different districts must also be 

 taken into account. 



The heaviest yielding month in Ceylon produced more than 

 four times the quantity of rubber harvested in the poorest 

 month (13.30 per cent in December, 2.91 per cent in March, 

 1914) and the crop of the Ceylon estates for the first six 

 months of 1914 was only 36.26 per cent of the total. In 

 Malaya the fluctuations between highest and lowest yielding 

 months are much less pronounced (9.94 per cent in December, 

 6.87 per cent in March. 1914), while in the first six months 

 of 1914 the Malaya estates harvested 45.49 per cent of the 

 total crop. 



It would also appear that machinery and drying space re- 

 quired should be less in Malaya, where monthly outputs do 



not show any extreme fluctuation, than in Ceylon, where as 

 much as one-seventh of the year's crop is harvested in a 

 single month. 



The charts show that there is no great variation in crop 

 percentages between 1913 and 1914 in either country. 



COAGULATION OF LATEX. 



A WRITER (L. E. C.) in the "Tropical .Agriculturist" 

 ^~* (October, 1915) submits some remarks on rubber latex 

 coagulation. There seem to be several well-defined stages 

 in the degree of coherence of rubber separated from latex. 

 These are creaming, flocculence, agglutination and coagu- 

 lation. 



Creaming is the condition observed in the early stages of 

 slow coagulation when the latex thickens. 



Flocculence refers to the formation of small particles of 

 rubber without coalescence into lumps. This state is ob- 

 servable in latex to which much formalin has been added. 



Agglutination applies to local or lumpy coagulation ob- 

 served when latex coagulates spontaneously, or when certain 

 mineral salts are added. 



Coagulation proper is the final stage observed on careful 

 addition of acids to latex, the rubber forming in one clot and 

 leaving a clear liquid. 



In rubber latex there is a suspension of rubber particles 

 which subsequently form rubber; also at the same time there 

 is present, in solution, a number of bodies which are of the 

 protein class. These proteins are in colloidal solution and 

 are capable of being precipitated by certain reagents, notably 

 acids. It seems probable that this protein acts as a protective 

 colloid to the pure caoutchouc present. The theory of this 

 protective action is that a combined solution and suspension, 

 such as this, acquires many of the characteristics of the sub- 

 stance in colloidal solution. It has been suggested that this 

 protective action is due to the absorption of a layer of the 

 dissolved protective agent over the surface of each of the 

 suspended particles. It seems probable that this is so in the 

 case of the rubber particles, in view of the fact that it does 

 not behave as a pure suspension, but that its coagulation 

 reactions resemble in many respects those of certain proteins. 

 Not all the nitrogenous constituents of latex, however, are 

 precipitated with the rubber during the ordinary process of 

 coagulation. 



The effects of anti-coagulants involve the action of many 

 factors. The anti-coagulant may be an alkaline substance 

 acting to neutralize acid formed in the latex by decomposition 

 or fermentation, or as a retarding agent on the coagulating 

 enzyme said to exist in the latex. When formalin has been 

 added to latex in certain proportions it apparently acts as 

 a retarding agent, since the latex will retain its milky appear- 

 ance and the rubber does not form a clot; but, actually, the 

 latex loses its original nature and consists of a number of 

 particles of rubber in suspension in a clear liquid. In this 

 connection it may be noted that formalin is a coagulant of 

 certain protein bodies. 



In the coagulation of rubber latex by the Brazilian and 

 other processes of smoking, the effect of heat enters very 

 largely into the operations. In the Wickham process the 

 author finds that, if the temperature of the jet of smoke im- 

 pinging on the layer of latex be less than 140 degrees F., 

 coagulation is not obtained. Heat alone, at this and slightly 

 higher temperatures, will coagulate fresh latex. Latex heated 

 to 140 degrees F. will coagulate with a certain quantity of 

 acid almost immediately, whereas normally it would have 

 required some hours. 



Rei)lete with information for rubber manufacturers— Mr. 

 Pearson's "Crude Rubber and Compounding Ingredients." 



