54 o SCIENCE PROGRESS 



tapped once. At the same time it practically quadrupled the 

 yield to be expected. 



At about this same time the Director of the Botanic Gardens 

 in Singapore commenced to push rubber cultivation, and that 

 with considerable success, as the planters in the Malay Peninsula 

 were in very low water owing to the low prices of coffee, and 

 had not, like the Ceylon planters, stable and prosperous indus- 

 tries such as tea, cardamoms, coco-nuts, cacao, and so forth. 

 The result has been that Malaya has rather more older trees 

 at the present time than Ceylon, though it has not so large 

 an area planted. 



During the following year, 1898, Mr. John Parkin was in 

 Ceylon as Scientific Assistant at the Royal Botanic Gardens, 

 and worked out the question of the w r ound-response in detail 

 (the figures above given are some of his). He came to the 

 conclusion, which has not as yet been generally accepted, 

 that the latex, in Hevea at any rate, is mainly of the nature 

 of a water-store, the plant drawing upon it in dry weather, 

 when the latex is found to be much thicker, and richer in 

 caoutchouc. 



In addition to this, Mr. Parkin worked out in detail the 

 method of making " biscuits " which has been universally 

 followed ever since in Ceylon and Malaya (for the sheet is 

 simply a larger biscuit). Biffen had shown that the essential 

 constituents of the smoke used to clot the rubber in South 

 America were acetic acid and creosote, and Parkin applied 

 this to the coagulation of the latex. Collecting it in tins 

 containing a little water (to prevent immediate coagulation) he 

 then mixed with it the calculated amount of acetic acid and 

 a little creosote, clotting the latex into the form of the 

 vessel in which the reaction was performed. It was then 

 rolled, and hung up to dry. This process has been used 

 ever since in Ceylon, and, as the milk is filtered before 

 coagulation, a pure biscuit is obtained, getting on the open 

 market a very high price. 



On the strength of these results of 1897-9, many people 

 began to plant rubber, but the rapid extension of the cultiva- 

 tion was checked till about 1902 by the scarcity of seed. 

 After that time, a vast quantity of seed began to be also 

 available from private sources, and extension of cultivation 

 has gone on rapidly, so that now there are about 105,000 



