Gums, Resins, 



508 



[December, 1908. 



The rubber was valued at 5s. Id. per 

 lb. in London, with fine hard Para from 

 South America quoted at 4s. 7d. per lb. 

 aud Para biscuits from Ceylon and the 

 Federated Malay States at 5s. Id. to 5s. 

 7M, per lb. 



Sample No. 6, also derived from tree 



A, was a very thin biscuit of pale yellow 

 rubber, weighing about i oz. It ex- 

 hibited good elasticity and tenacity and 

 was quite equal in quality to samples 

 1 and 4 ; it was, however, too small for 

 separate examination. 



Nos. 2 and 5. '"Para rubber. Tree 



B. Age 30-35 years. Natural coagula- 

 tion." Weight 7 oz. 



Two biscuits of rubber ; one 6 inches 

 in diameter and nearly § inch thick, 

 the other 4 inches in diameter and from 

 s to j inch thick . 



The rubber w T as light coloured, clean, 

 well prepared, and free from stickiness, 

 but was not quite so strong as the 

 rubber from tree A. 



The results of the analysis were as 

 follows : — 



Rubber as Composition of 

 received dry rubber. 

 Per cent. Per cent, i 



Moisture 



Caoutchouc 



Resin 



Proteids 



Ash 



3'7 

 89-3 

 3-6 

 2-6 

 08 



The rubber was valued at 4s. 

 lb. in London. 



92-7* 

 3-7 

 2-7 

 0-8 



lid. 



per 



These sam pies of rubber from tree B 

 were slightly inferior in physical 

 properties to the specimens prepared 

 from tree A, and the value assigned to 

 the rubber is correspondingly lower. 

 The only noteworthy difference in the 

 composition of the rubber from these 

 two trees is that the product from tree 

 B contains a much higher percentage of 

 "insoluble caoutchouc" than that from 

 tree A. 



No. 3. "Para rubber. Latex from 

 trees A and B mixed. Natural coagula- 

 tion." Weight 4 1 oz. 



The specimen was & thick biscuit 

 about 5 inches in diameter and from § 

 to 5 inch thick. The rubber was dark 

 coloured externally but white within, 

 rather porous and moist, and possessed 

 a slight disagreeable odour ; it exhibited 

 good elasticity and tenacity. It was 

 not submitted to chemical examination. 



* Soluble in chloroform 87'4 per cent ; insoluble 

 in chloroform 5 '3 per cent, 



Owing to the thickness of the biscuit 

 the rubber had not thoroughly dried, 

 and its moist character adversely 

 affected its market value. The specimen 

 was valued at 4s. 3d. per lb. in London. 



Castilloa Rubber (Castilloa elastica). 

 No. 10. " Castilloa rubber from trees 

 7h years planted." Weight 6 oz. 



A thick cake of rubber, 5 inches in 

 diameter and from | to i inch thick. 



The rubber was almost black exter- 

 nally, but greenish-white within when 

 freshly cut ; it was clean, slightly sticky, 

 and exhibited very poor elasticity and 

 tenacity. 



The results of the analysis were as 

 follows : — 





Rubber as 



Composition 





received 



dry rubber. 





Per cent. 



Per cent. 



Moisture 



... 2-5 





Caoutchouc 



... 46-4 



47-5 



Resin 



... 50-6 



52-0 



Proteids 



... 0-5 



0-5 



Insoluble matter 



nil 



nil. 



Ash 



.. 0-24 



0-25 



This sample of rubber is of inferior 

 quality on account of the very high 

 percentage of resin present. It was 

 valued at 2s. per lb. in London. 



No. 11, "Castilloa rubber from trees 

 1\ years planted." Weight 8£ oz. 



A thick cake of rubber, 6 inches 

 in diameter and 1 inch thick. The rub- 

 ber was almost black externally but 

 lighter within, clean and slightly sticky; 

 its physical properties were not very 

 satisfactory, although it was superior 

 in this respect to the preceding spe- 

 cimen No. 10. 



The rubber had the following composi- 

 tion : — 



Eubber as 

 received. 



Composition 

 of dry rubber. 





Per cent. 



Per cent. 



Moisture 



25 





Caoutchouc 



. 57-6 



59 1 



Resin 



36-0 



36 9 



Proteids 



1-0 



l'O 



Insoluble matter .. 



. 2-9 



3-0 



Ash 



. 2-4 



2 5 



This sample contains less resin than No. 

 10, but the amount of this constituent 

 is still very much greater than is admis- 

 sible in rubber of good quality. It was 

 valued at 3s. per lb. in London. The 

 scrap rubber, sample No. 12, correspond- 

 ing to Nos. 10 and 11, was valued at 2s. 

 lOd. per lb. 



