Gums, Resins, 



196 



[March, 1910. 



articles are liable. The non-resistance 

 of rubber substitutes to the action of 

 potassium hydrate is the method used 

 for the detection and estimation of 

 substitutes. Among the multifarious 

 substances proposed to be employed for 

 diluting rubber the oxidation-products 

 of drying-oils are the basis of the main 

 modern class. Dry oxidation of a 

 suitable fixed oil, usually linseed oil, is 

 effected with manganese dioxide, etc., 

 or in the wet process nitric acid is used, 

 the object being to form elastic sub- 

 stances similar to linoxyn. Stiffeners 

 such as resin, pitch, tar, acacia, traga- 

 canth, and albuminoids such as gelatin 

 or casein, may be added, as also " filling " 

 materials including chalk, magnesia, 

 silica, kaolin, zinc oxide, cork, sawdust, 

 chopped feathers, and waste leather. 

 The product is vulcanised in the usual 

 manner, frequently with the addition 

 of waste or regenerated rubber, and is 

 then used for lower-grade goods. The 

 elastic product yielded by heating 

 nitrated castoi oil to 130° C. for ten hours 

 is the subject of a patent by the Velvril 

 Co. Passing ozone through a mixture of 

 castor oil containing colophony and 

 sulphur is a variation of the oxidation 

 process patented in America, the pro- 

 duct being finally heated with sulphur 

 chloride. Ditmar (1900), in his specifi- 

 cation for a process for the removal of 

 unvulcanised oil by means of solvents, 

 states that the defects in substitutes are 

 due mainly to its presence. Gelatin or 

 glue, with or without admixture of 

 glycerin, rendered insoluble by treat- 

 ment with formaldehyde or chromic 

 acid, gives another form of rubber 

 substitute. The viscous masses ob- 

 tained by heating carbohydrates such as 

 sugar and starch, are the subjects of 

 patents, as also elastic plastic masses 

 stated to result from the action of 

 acetylene and oxygen on a mixture of 

 copper and nickel, the metals acting as 

 catalyst. Rouxville (1900) filed a speci- 

 fication in France for producing caou- 

 tchouc, etc., from terpenes (turpentine), 

 but did not' complete the patent in 

 England. The conclusion arrived at is 

 that cheaper rubber of improved quality 

 is more likely to be derived from in- 

 creased production by recent rubber- 

 plantations than by artificial production. 



GUTTA-PERCHA CULTIVATION. 



(Prom the India Rubber Journal, Vol. 



XXXVIII, No, 12, December, 1909.) 



From a number of communications 

 which have been received at this office, 

 it would appear that the possibilities of 

 cultivating gutta-percha is receiving a 



certain amount of attention in different 

 quarters. The idea is not, of course, a 

 new one ; it occurred to Teysmann, of 

 the Botanic Gardens, Java, in 1856, and 

 was acted on by him in the same year, 

 with the result that the Netherlands 

 Indies Government have now a con- 

 siderable area under this product. 



In the " Sourabaya Handelsblad " some 

 little time ago appeared an article on 

 the subject in which attention was 

 called to an alleged deficiency of seed- 

 bearers in the Straits and F. M. S. Mr. 

 H. N. Ridley, of the Botanic Gardens, 

 Singapore, replied in a letter, which was 

 at the same time an assurance that 

 sufficient seeds were available in case of 

 a demand springing up, and a denial 

 that gutta-percha cultivation was com- 

 mercially attractive. 



In Singapore there are a large number 

 of cultivated plants, and the trees may 

 be found growing wild in parts of the 

 Island, while in Penang there are many 

 fine fruiting trees. Large areas in the 

 F. M. S. have been found rich in this 

 plant, and these, by a system of 

 clearing the unnecessary vegetation 

 and planting the blanks with seed- 

 lings, have been converted into 

 extensive cultivations. Gutta percha 

 does not, however, possess the impor- 

 tance as a commercial product which it 

 did in the past, and in Mr. Ridley's 

 opinion it is not likely to regain the 

 position it then held. Thus, though its 

 cultivation is by no means neglected in 

 British Malaya, it has not been con- 

 sidered worth while to cultivate it so 

 elaborately as at Tjepetir, 



Dr. A. H. Berkput, who has contributed 

 to the India Rubber Journal (April 6, 

 1908) an interesting article on the culti- 

 vation of gutta-percha in Java, agrees 

 with Mr. Ridley as regards the inadvis- 

 ability of private planters taking up the 

 cultivation, at least until the problem of 

 the preparation of leaf gutta has been 

 solved. Palaqium gutta has been found 

 the most satisfactory tree to plant, but 

 the yield is low compared with that 

 obtainable from Para rubber, etc, and 

 the waiting period long. On the Govern- 

 mant plantations it is calculated that 

 the ultimate cost will amount to £25 per 

 acre. Calculating a yield of 50 lb. per 

 acre in alternate years — that obtained 

 from some 23 year old trees near 

 Buitenzorg — it will be seen that large 

 profits cannot be looked for. Tapping 

 in alternate years is necessary owing to 

 the slow w T ound response. 



A correspondent of the "Straits Times' 

 takes a more optimistic view. In the 

 first instance, he thinks, the statistical 

 position of gutta-percha compares very 



