Gums, Resins, 



392 



[May, 1910. 



treated, the renewed bark on the first 

 area will be sufficiently mature to allow 

 the multiple tapping to be recom- 

 menced. 



Two important points should be 

 observed in modern tapping. The 

 wound should be re-opened by as thin a 

 paring as possible ; and every care 

 should be taken not to injure the 

 cambium. The longer the bark can be 

 made to last, the greater, as a rule, 

 will be the yield of rubber. Shavings 

 of bark one-twentieth of an inch or 

 even less in thickness are now managed 

 in practice. A foot of bark can, there- 

 fore, be made to last for about 250 

 successive tappings. 



A wound which passes through the 

 cambium into the wood heals badly. In 

 the excision method of tapping careless 

 manipulation results in an uneven bark 

 renewal, producing a surface difficult to 

 tap in a systematic manner. Conse- 

 quently to guard against cambial injury 

 and to ensure thin parings much inge- 

 nuity has been exercised in devising 

 suitable tapping instruments. At least 

 two dozen different knives have already 

 been invented for the purpose. Some of 

 these have met with favour and are 

 commonly used.* 



Pricking. — Since economy in bark 

 excision is so important, the idea that 

 puncturing might be substituted to 

 some extent for paring was early mooted, 

 A tool, termed the pricker, was brought 

 out for the purpose. Good yields were 

 obtained by the combined use of the 

 parer and pricker. The bark was thus 

 made to last longer. 



Recently a Ceylon planter t has intro- 

 duced a pricking system as a complete 

 substitute for the paring method. It 

 has not as yet met with much favour. 



Pricking has been blamed for the 

 production of burrs and nodules in 

 the renewed bark Petcht has stated 

 reasons for this view. If correct, it is a 

 serious drawback to the use of the 

 pricker. Though opinion generally 

 seems rather opposed to than in favour 

 of pricking, either in conjunction with 

 paring or alone, yet it is still a debatable 

 point. The paring method on the half 



* For details the reader is referred to Wright's 

 text-book, pp. 79-88 ( Hevea brasiliensis oi Para 

 Rubber, 3rd edition, 1908), and to the page of the 

 India Rubber Journal for the latest knives. 



f North way's Tapping System— see article in 

 India Rubber Journal 1909, Vol. xxxviii., p. 225. 



I Petch, Circular. Royal Botanic Gardens, 

 Ceylon, 1909, Vol. iv„ No. 18, 



herring-bone system is giving excellent 

 results on estates and is very systematic. 



The question may be asked : Will 

 the tree stand this somewhat severe 

 treatment of removing gradually its 

 bark up to a height of six feet ? So far, 

 no pronounced ill-effects have shown 

 themselves. The bark on the excised 

 area is renewei satisfactorily, and this 

 secondary covering is as rich or even 

 richer in latex than the primary bark. 

 This is on a par with the cinchona tree, 

 which gives a greater yield of quinine 

 from its renewed bark. 



It has not yet been settled as to the 

 time which should elapse before the 

 reformed bark should be tapped. Four 

 years has been considered a suitable 

 period, but this may be possibly longer 

 than is really required. Some results 

 seem to show that if the new bark is 

 tapped early, the rubber is of an inferior 

 quality, even though the latex may be 

 abundant. 



Wickham* in his criticism of planta- 

 tion methods, views with disfavour this 

 system of removing the bark, and thinks 

 that, in the long run, the iucision mode 

 of tapping, as employed on the wild 

 trees in the Amazon, will be found to be 

 preferable. His views seem generally 

 to run counter to the practices in the 

 East. At the same time, the opinions of 

 one who is so well acquainted with the 

 Brazilian rubber industry are not to be 

 lightly laid aside. 



High Tapping .—It has already been 

 mentioned that, as a rule, it is not advis- 

 able to continue the tapping of a Hevea 

 tiunk above six feet. In the first place, 

 the yield of latex is much less from the 

 upper parts of the stem ; and secondly, 

 high tapping requires the erection of 

 scaffolding, which adds greatly to the 

 expense. 



Interesting experiments as to yield 

 have been carried out by the Ceylon 

 Botanic Gardens Departmentt on the 

 original Henaratgoda tree. These bring 

 out clearly the great rubber- producing 

 capacity of the basal six feet of trunk 

 and the small yield afforded by the 

 higher parts. 



The improbability of obtaining rubber 

 from the young stems, leaves, and unripe 

 fruits will be referred to in the conclud- 

 ing portion of this paper, which will 

 deal chiefly with the preparation of the 

 rubber from the latex. 



* Wickham, toe. cit. p. 38. 

 t Royal Botanic Gardens, Ceylon, Adminis- 

 tration Report, 1906, p, 32. 



