126 AGRICULTURE IN THE TROPICS [PT. II 



proved to give a yield at six or seven years old instead of ten, 

 the yield has been larger, and the price of rubber has risen 

 enormously in the last few years. The profit of 27 / Q was 

 estimated on a yield of 100 Ibs. an acre, selling at 2s. a lb., 

 whereas the same yield has been obtained three years sooner, 

 and sold at nearly 6s. a lb. This price of course could not be 

 expected to last, and in the end of 1907 and beginning of 1908 

 it has fallen to 4s. 



Not only did Mr Parkin work out the wound-response, and 

 thus change what appeared to be only a moderately remune- 

 rative industry into a very profitable one, but he also worked 

 out the way of coagulating rubber into " biscuits," the form in 

 which the bulk of the cultivated Para rubber has hitherto 

 appeared on the market (for the sheets of Malaya are simply 

 larger biscuits). Instead of allowing the latex to run down the 

 tree, and thus become dirty, and instead of allowing it to dry 

 into a mass of dingy black rubber in a coconut shell, he showed 

 that it could be collected in little tins, placed one under each 

 cut, and then mixed together and coagulated by the addition of 

 the calculated amount of acetic or other acid. The milk having 

 been filtered before clotting, this resulted in the formation of 

 clean "biscuits" free of all tangible dirt, which is so largely 

 present in all the wild rubbers of commerce. These biscuits 

 as a matter of fact lose but little in the washing and drying 

 through which crude rubber subsequently goes. 



During the last five years, a very large trade in rubber 

 biscuits and sheet has sprung up between Ceylon and the Malay 

 Peninsula and the markets of Europe, though of course the 

 amount so far exported is a mere drop in the bucket as 

 compared with the consumption. The prices obtained for this 

 clean rubber have been from 6d. to 8d. per lb. higher than 

 those given for the best South American rubbers, and this is 

 often supposed by planters to mark a real superiority. It is 

 very difficult to get at the truth, but the fact seems to be that 

 manufacturers generally object to the dry cultivated rubbers as 

 lacking in strength and resiliency, and are using them as yet 

 for the manufacture of solution, for which their cleanliness more 

 especially fits them. The higher price paid for the cultivated 



