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The Supplement to the Tropical Agriculturist 



colour, and the resin content is less. It is, 

 therefore, a better rubber, as far as can be 

 judged without vulcanisation tests. 



TaBERJSTAEMONTANA DlCHOTOMA. (INDIA.) 



The specimens examined in the Botanical 

 Gardens were trees about fifteen feet high, of a 

 girth near the base of about eighteen inches, 

 and were growing in a very exposed place in 

 poor soil. Two of these trees were tapped on 

 successive mornings. The latex ran slowly. It 

 coagulated in a few hours in the bottle in spite 

 of added formalin. On rubbing between the 

 lingers and thumb it leaves them sticky as a good 

 rubber latex should not do. The solid mass was 

 extracted. The figures on the dry weight are : — 

 Gutta, 25'95 per cent. ; Resin, 74"05 per cent. 



The latex contained 40'2o per cent of solid 

 material. The extracted gutta beerus to be of 

 very good quality, very tough and of a light 

 yellowish colour. It is very hard when cold and 

 softens readily on warming. The resin appears 

 not to contain cinnamic acid esters, although 

 further work would be necessary to decide this 

 point. It would seem as if the extracted gutta 

 might be a very useful substance. 



LliUCONOTIS EuGENIIFOLlUS. 



The specimen examined was a low bush in 

 the Botanical Gardens, a mixture of Leuconotis, 

 Willughbeia and Drceola. Great care had to be 

 taken to trace each stem to its proper leaf. The 

 thickest stems procurable were tapped trans- 

 versely ; a small amount of thin latex was ob- 

 tained. Acetic acid coagulates this latex readily 

 but on analysis it was found to contain no rubber. 

 The main constituent, comprising 26 - 19 per cent 

 of the whole latex, is a sticky resin soluble in 

 acetone. 



Artocarpus Integkifolia. 



The specimens examined were common Jack 

 trees. The latex ran very well from herring-bone 

 tappings, It was thin and very sticky, neutral in 

 reaction to litmus. Attempts to coagulate it 

 were unsuccessful, but it was found the aggluti- 

 nated solid matter could be separated from the 

 serum by filtration on paper. A small percen- 

 tage only was found to be insoluble in acetone, 

 and this was found to be a white powder, neither 

 rubber nor gutta percha. Analysis of the latex 

 gave : 



per cenc. per cent 



Coagulum ... 2679 f Solid insoluble in 



Serum solids Gums «! acetone ... 2'37 



pectins, albumens, (_ Resin soluble „ ... 24 - 42 



etc. .. 8-85 .. .. 8-85 



Water ... 64 -36 ,. .. 61'36 



100. 100. 



The resin is a beautiful clear yellow, semi-solid 

 mass, and extremely sticky. This and a powder 

 of unknown nature are the chief components 

 of this latex, it containing no rubber whatever. 



Alstonia 11 Polai. : ' 

 The specimen examined was a large Alstonia 

 angustiloba tree in the Botanical Gardens. The 

 tree was tapped by the herring-bone system, 

 and the latex ran well at first, but speedily 

 thickened in the cuts as does Dyera latex. It was 

 kept going as well as possible by scraping it 

 down the cuts, and a total of 2 fluid ounces was 

 obtained. Addition of a measured amount of 



ammonia caused the latex to become much more 

 fluid and turn a bright yellow in colour. It was 

 filtered through a very tine mesh silk gauze to 

 remove dirt, and acidified with acetic acid. It 

 does not coagulate as easily as true Jelotong 

 latex with any ordinary coagulating agent. 



Analysis of the dry coagulum is : Rubber 

 22 "28 per cent, and Resin 77'72 per cent. 



Analysis of the pure latex gave : 



/"Rubber 7.83 per cent 



Ooagnlum 3.V74 por cent. -[ Resin 27'78 „ 

 (.Ash 013 „ 



I Organic 



Serum Solids 4-43 ,, i matter 3'78 ,, 



{ Ash 0-65 



Water 59-83 „ Water 59'83 „ 



100. 100. 



The latex thus strongly resembles that of 

 the allied Dyera tree. The coagulum, which is 

 rather stiff and brittle when the first exces- 

 sive amount of water has been removed, con- 

 tains exactly the same proportions of rubber 

 and resin as in the Dyera Jelotong. The serum 

 solids and the resin are very similar, they 

 may possibly be identical. The resins have all 

 the appearance of belonging to the amyrin 

 group of resin alcohols as do the true Jelotong 

 resins, Some of the chief differences between 

 the two latices are : 



(«) The inferiority of the Alstonia rubber. The 

 extracted rubber, although it seems to be caout- 

 chouc, is much inferior in strength and colour 

 to Jelotong rubber. 



(6) Inferiority of Alstonia latex as regards ease 

 of coagulation. 



(c) Tendtncy to turn bright yellow of the 

 Alstonia latex. If Jelotong rubber is adulterated 

 with pieces of "pulai" it often is possible to 

 detect the same by the yellow colour. On the 

 other hand if a small quantity of the ''pulai'' 

 latex is added to the Dyera latex it would be 

 quite impossible to detect it as the dry material 

 of both latices has exactly the same percentages 

 of rubber and resin. 



"Purub'' Jelotong. 

 A specimen of Jelotong coagulated by means 

 of "Purub" was examined. This was a large 

 hard ball, yellow outside and slightly so on the 

 inside. It was very hard and brittle and looked 

 very unpromising. The age was said to be about 

 three months. It probably contained some 

 "Pulai. ,; 



Au extraction showed that the rubber had 

 entirely degenerated to a very sticky gum. In 

 confirmation, a second extraction of a large 

 quantity was made with the same result. The 

 product is, therefore, absolutely worthless. 



Manihot Glaziovii. 

 The specimen examined was taken from a 

 large tree in the Botanical Gardens, Singapore. 

 The bark was quite unlike that of most rubber 

 plants, having a very thin outer bark. This 

 came away from the tree very readily when the 

 knife was used and a large surface of the same 

 was stripped back. On this exposed place, a 

 herring-bone tap was made, retapped again on 

 the following day, and again two days later. 

 The latex tubes are very near the outer surface 



