82 



The Supplement to the Tropical Agriculturist 



I had a small experiment conducted in the 

 latter part of the year with a view to deter- 

 mining the quantity and quality of rubber 

 these trees are likely to yield. One row 

 through the plantation containing 15 trees was 

 selected, one of which was considered 

 too small to tap ; but the results, as represen- 

 ting the produce of the plantation, have been 

 calculated on the total. They were tapped 

 on the half-spiral system and 3 times a week, 

 the period extending from 19th November 

 to 31st December. The latex was coagulated 

 with the addition of a little acetic acid and the 

 rubber prepared in biscuit form. 2 lb. oz. of 

 dry rubber were obtained, this being equivalent 

 to 32£ lb. per acre. Assuming that the trees are 

 given a rest of three months every year, this 

 works out at '206 lb. per acre per annum. The 

 rubber is of good quality and the result, consi- 

 dering the age of the trees, the nature of the soil 

 on which they are grown, and the season of tap- 

 ping (which was just previous to the wintering 

 of the trees) may be considered very satisfactory. 



It is evident that this rubber tree will grow 

 and yield well on the Gold Coast, and as our 

 trees are now seeding freely, I anticipate a some- 

 what extensive multiplication within the next 

 few years. Th9 natives who have already planted 

 it seem very pleased with its rate of growth, and 

 are asking for more plants. As a native culti- 

 vation it should be very profitable for it cau be 

 carried on in conjunction with cocoa, amongst 

 which it may be either planted as shade or set 

 in belts round the plantation ; but it is not likely 

 to succeed well if planted under jungle shade. 

 Ceara and Castilloa Robber. 



Ceara (Manihot Glaziovii) and Castilloa 

 (Castilloa elastica), two other varieties of rub- 

 ber trees, have been introduced, but neither of 

 them are at all promising. The former suc- 

 ceeds best in the dry zone and it is just possible 

 that it may grow more satisfactorily in the 

 Northern Territories, where, on the establish- 

 ment of a station next year it will be given a 

 trial. The Castilloa would not appear to be at 

 all suited to this coast, for, besides showing 

 only a very indifferent growth, the trees are 

 badly attacked by a longicorn beetle which 

 practically destroys them.— Official Report for 

 190S of W. S. Tudhope, Director of Agricul- 

 ture, Gold Coast. 



NEW LEGUME FOR RUBBER. 



[To the Editor, "Malay Mail.''] 

 Sir, — I shall feel greatly obliged if you will 

 kindly publish tho following in your esteemed 

 columns. Mr. J. B. Carruthers, Director of Ag- 

 riculture and Government Botanist, Federated 

 Malay States, in his report for 1908 on cover 

 plants, sums up his ideal plant as follows : — 



" The ideal plant for the purpose of protecting rubber 

 land and eliminating or reducing very considerably the 

 weeding bill is a plant which grows not more than a foot 

 to 18 " high, is permanent for 3 or four years, producing shade 

 over the ground, growing so luxuriantly as to exclude weeds, 

 without forming a thick" turf, is leguminous, has no thorns 

 or spikes to interfere with coolies working, has no leaves, 

 fruit or flower which will attract vermin or other animals. 

 None of the plants at present in use or being tried in the 

 experimental plots of the >.giicul tural Department fulfil ab- 

 solutely all these requirements, and it is probable thatplant 

 will yet be found, better than any yet at present tiied." 



He then mentions a number of cover plants, 

 but none of them come up to his ideal. I there- 

 fore presume the "cassia mimosoides : ' is a 

 stranger to him, as he does not mention it, and 

 funnily enough it's a legume that comes as 

 close to his ideal as I fancy will ever be found. 

 To enumerate — it's a fiat spreading leguminous 

 plant, absolutely thornless, sensitive in so far 

 that it closes its leaves at night and during rain, 

 opens directly the sun shines and thus conserves 

 moisture, grows thick to the exclusion of weeds 

 is in no way turfy, does not attract vermin as 

 far as my experience goes (I vouch for this as 

 this district is rich in vermin of sorts), grows 

 quickly, is a particularly free seeder, and if not a 

 permanent cover will certainly resow itself socon- 

 tinuallythat theground will never beclearof it un- 

 less desired to be forked in as a mulch. Another 

 advantage : it saves wash during heavy rain. 



The plant grows well at all elevations. Its 

 height will, I am sure, never exceed 18" at the 

 lowest altitude and from 4,000 to 6,000 feet 

 above sea level it grows practically flat. There 

 is no doubt that it will as a cover plant rich in 

 nitrogen suit all products. I do not know Mr 

 Carruthers' address, but if he or any planter in- 

 terested in the subject wishes for any further 

 information I shall always be happy to reply. — 

 I am, etc., 



Phil. Beaver. 

 Sholarock Estate, Katary P. O , Nilgiris, S. 

 India. Nov. 25th, 1909.— Malay Mail, Dec. 11. 



CAUSE OF TACKINESS IN RUBBER. 



Dr. Fritz Frank, in a communication to the 

 "Gummi Zeitung," attributes the occurrence of 

 "tackiness '' in certain raw rubbers to the pre- 

 sence in the rubber, as coagulated, of imper- 

 fectly polymerised portions, which owe their 

 existence to unsatisfactory methods of coagu- 

 lation. In the smoking process employed in 

 the case of tine Para, every portion of the latex 

 comes under the influence of the coagulating, 

 polymerising agent, and " tackiness" is normally 

 absent. When a mass of raw rubber containing 

 imperfectly polymerised portions is subjected 

 to mechanical working, the faulty portions be- 

 come distributed through the mass, upon which 

 they exercise a solvent action resulting in 

 general deterioration. The presence of water 

 in the raw rubber tends to check any action of 

 this kind. It is possible that bacterial or enzyme 

 action may play a part in the spread of tacki- 

 ness, the heat generated either rendering the 

 sound rubber more liable to attack (solution), or 

 even bringing about a direct depolymerisation. 

 The following precautionary measures are 

 advocated : (1) Intimate mixing of the coagu- 

 lating agent with the latex. (2) Use of only 

 small quantities of latex at a time, in all cases 

 where the process employed is such as to render 

 likely the formation of lumps and consequent 

 inclusion of uneoagulated latex. (3) Protection 

 of the coagulated rubber from the action of light 

 and heat. (4) Minimum mechanical treatment 

 of the rubber at the place of origin. (5) Packing 

 in cases, and storage m cool places during 

 transport. (6) Presence in the raw rubber of 

 a certain amount of moisture. — India Rubber 

 Journal, Nov. 29. 



