The Supplement to the Tropical Agriculturist 



"PURUB"~A NEW METHOD OF 

 COAGULATION. 



By Dr. Frank. 



It is a well-known fact that hydrofluoric acid 

 is wonderfully efficient in preserving plant-saps, 

 and that is also has the power of killing the wild 

 yeast in the fermentation process without in 

 any way influencing the alcoholic fermentation. 

 Furthermore, the fact that this substance acts 

 in extreme dilution induced Sandman to experi- 

 ment with hydrofluoric acid. The results are 

 extremely satisfactory, since all the advantages 

 of the smoking process are secured, while the 

 drawbacks of this method disappear. The pro- 

 cess is carried out in the following manner : — 



The hydrofluoric acid comes on tho markets 

 as "Purub," in a condition enabling it to be 

 easily shipped. The latex is strained through 

 a cloth to remove the mechanical impurities 

 and, if necessary, diluted to prevent spontaneous 

 coagulation. The working charge is about 2 or 

 3 litres. To 1 litre latex is added a mixture of 

 50 grs. water and 5 c. c. Purub solution. After 

 adding the diluted Purub the mass is stirred 

 and then allowed to stand. The rubber which 

 has separated out soon begins to collect as a 

 compact mass on the surface of the almost clear 

 liquid. The coagulated mass is removed and 

 washed. It is then either pressed in the pri- 

 mitive manner with a wooden press or else rolled 

 out. The resulting strips can then be pressed 

 into blocks in the wet state, or after superficial 

 drying, and are then ready for shipment. The 

 quantity of latex per charge is limited only by 

 the size of the vessels employed and the 

 means at hand for manipulation. It is readily 

 seen that in this manner a workman is 

 capable of working up a large amount of latex 

 in five hours without exerting himself to any 

 extent, and without being in the least incon- 

 venienced. On the other hand, an industrious 

 workman is scarcely able to work up more 

 than 20 litres of latex in five hours by . the 

 smoking method. 



The results so far show that rubber obtained 

 by the Purub process has not the least ten- 

 dency to ferment or decompose. The rubber, 

 furthermore, is in a good state, physically and 

 is very easily worked up. These properties 

 are easily explained if one studies the state- 

 ments made above. Any bacteria liable to cause 

 decomposition are killed, and their re-forma- 

 tion prevented. The adhering of the particles 

 takes place under conditions which effect the 

 toapletest distribution of the antiseptic, since 

 no sudden coagulation is brought about. The 

 manipulation of the process is simple. 



It seems only necessary to mention the ob- 

 served fact that the rubber obtained by the 

 Purub method vulcanises exceptionally quickly, 

 so much so that the sulphur is in complete 

 combination with the rubber before it com- 

 bines with any litharge present in the mixing. 

 — India Rubber-Journal, Sept. 21. 



FROM A BIG RUBBER DISTRICT. 



A proprietary planter writes to us : — 

 "We have been very interested to hear of your 

 Senior's enterprising trip to Sumatra and Java, 

 of which, no doubt, we shall read more soon 



in the Observer- The only fear is, it may 

 disgust him to compare what he has seen 

 there with the somewhat poorer growth of 

 rubber in Ceylon. But as my argument always 

 was when in olden days in Dikoya, I heard 

 invidious comparisons made with Haputale : 

 ' Wish them joy in their better luck as long as 

 it does not interfere with you, and you can make 

 £5 an acre out of your coffee instead of £10 ! : — 

 and the worst I can say here of our holding 

 is, that if prices keep reasonably near pre- 

 sent quotations we are likely in this part of 

 the world to realise the former anyhow, 

 and possibly something better. I find in 

 exposed parts, wind the worst enemy, which, 

 no doubt, will yield to abundant plantings of 

 albizzias, &c, and the system of cultivation 

 adopted has a tendency, probably, to retard 

 the growth of the trees in their early stages — 

 though, looking ahead, its advantages over clean 

 weeding can hardly be questioned. I have trees 

 ' 2 years and 9 months old from seed ' up to 19 

 and 20 inches in circumference at foot — and alas! 

 some not 6 inches ! We mean to cultivate fairly 

 liberally — the benefit of which should show 

 in a year or so. My question is : will 300 acres 

 of rubber suffice to give a moderate income 

 permanently? The 'fiver' will amply content me, 

 and looking at things squarely I do not see 

 that it is too much on the unit to expect ! The 

 trend of present industry and requirements 

 seems to me to point imperatively to the rapidly 

 increasing rise of rubber, such that, if no 

 adequate substitute is found, the natural sup- 

 ply will hardly be able to do much more than 

 keep pace with it in the future. Let us hope 

 so — plenty of labour: no fatalities ; and rubber 

 pavement universal." 



TEA CULTIVATION IN NYASALAND 

 PROTECTORATE. 



The report for 1907-8 on theNyasaland Protec- 

 torate, recently issued by the Colonial Office, 

 gives the following details respecting the culti- 

 vation of tea in that Protectorate : — 



The cultivation of this product is still con- 

 fined to the Mlanje district, where the soils 

 and climate are well suited to its growth. There 

 are now 516 acres under tea, and this area is 

 being increased yearly. The crop for 1907-8 is 

 stated to have been 2\ tons, and 9£ tons are 

 estimated for the present year. Much of the 

 tea at present produced is consumed in the 

 country. Tea cultivation is not taken up with 

 eagerness by planters, as a period of five or 

 six years has to elapse before any return is 

 made on the capital expended. 



It is well known that the quality of tea im- 

 proves as the bush matures, and those who 

 tasted the locally-grown and manufactured 

 article three years ago, now report that a great 

 improvement has taken place in the quality. 

 Tea cultivation requires a good deal of capi- 

 tal, but it is understood that it can be pro- 

 duced in Nyasaland at a cheaper rate than is 

 possible in India or Ceylon. As soon there- 

 fore, as Nyasaland tea obtains a footing on the 

 London market, it should draw attention to 

 that country as a possible field for the invest- 

 ment of capital. — Board of Trade Journal, Oct.l, 



