Vol. VII. Xo. 169. 



THE AGKICITLTOEAL NEWS. 



.327 



of these machines have teeth about 1 inch bnxul for entering 

 and breaking uj) the soil, while others are fitted with shovels 

 2 to 3 inches broad, wliich may be substituted by sweej)s 12 

 inches in lireadth. Other implements again are fitted with 

 spring teeth or with discs for the same purpose. 



^lachines of the above type.s are drawn by one or by 

 two hor.ses. The one-horse implement pa^es down the space 

 between two rows, while the two-horse maMiiiie straddles the 

 row of plants, a horse (or mule) walking, on each side. It 

 is obvious that the former implement can be used later in 

 the growing period of the plants tlian the two-horse machine, 

 being able to jiass between the rows of; jilants when the 

 latter have grown too tall to be straddle<l without injury by 

 the two-horse machine. 



The depth at v.-liich these implements work I'an, in 

 most case.s, be easily regulated, and many of them are made 

 «o that their width can be easily altered U> suit llie varying 

 distances between the plants. 



On my estate in Tobago I am at prt^sent working a one 

 horse cultivator known as the ' Planet Junior ' (No. 9), which 

 is proving a very useful machine. It is neat, strong in make, 

 and can easily be drawn by a pony. The cultivator is fitted 

 with five pointed shovels, four of which aife about 2.', inches 

 wide, while the fifth is about 4 inches iu breadth. These 

 shovels are arranged two in front and three behind, lirnad 

 sweeps can be obtained which can be .Substituted for tJie 

 three rear shovels ; and for shallow work, such as is required 

 in cotton cultivation, these are strongly recommended. 



The ' Planet .Junior ' machine is fitted with a wheel in 

 front, and the depth at which the macliine is reipured to 

 work is regulated liy raising or lowering this wheel. It is 

 most important that the planter himself thould arrange the 

 depth at which the machine shall work. Some cultivators 

 are fitted with a lever for altering the politicni of tht^ wheel, 

 but, in my opinion, a machine with a whtel the jjosition of 

 which can only be altered by taking oul a bolt (as in the 



■ ca.se of 'Planet Junior,' No. 9), is preferaHe. 



With a good pony an area of about ■; acres per day can 

 be cultivated by means of the machine refeired to. The 

 price of the implement is about •'JIO'OO. 



In regard to the use of these mechfiiical cultivators at 

 Barbados, it has been stated by planter.s tiat they' might be 

 worked with advantage on the red soils of the island, but 

 that they would be of no use on the black soils. When the 

 soils of the latter kind are in a sticky conation, it is |)ossible 

 that the uiachines would be of little value but i)rovided they 

 were fitted with sweeps, I believe the iinjlements would do 

 •excellent work even on the black soils, <i» soon as the stii'ky 



■ condition has passed. ' 



RUBBER EXPORTS FROM BAHIA. 



The exports of rubber from the rhazilian iState of 

 Bahia fell off considerably in 1907, as* iompared with the 

 two previous years. In 1905, and agiiji in IDOli, about 

 1,400 t<ms were shipped, but in 190? !he exports fell to 

 1,0.H(5 tons, having a value of £219.401. As in the case of 

 cotiee, a product which also shows a diminition in the exports, 

 the decline is attributed to genei-al trade depression in the 

 United States, to which country most of tie rulilier jii-oduced 

 in Bahia is .shipped. 



The rubber of Bahia is of two kinds, tnown respective- 

 ly as Manicoba, the produce of a species tf Manihot (but 

 not to be confounded with Ceara rubber from MauUiof 

 Gliuiovii) and Mangaheira, ])roduced f'pm llnncoriiia 

 qieriom. Neither of the-se kinds is equalto Para rubber. 



TREATMENT OF LATEX IN THE 



PREPARATION OF RUBBER. 



The causes of discoloration in rubber, and a suitable 

 method of preventing this, so that the finished product 

 can be put on tiie market, uniform in appearance and 

 character, are dealt with by Mr. Kelway Bamber, F.I.C, 

 in the following article, which appeared in the BiMiiiii. 

 of the Straits and Federated ;Ma!ay States of August 

 last : — 



A point of considerable importance in the manufacture of 

 plantation rubber is to obtain not only jturity, but constant 

 uniforniity in the finished product. At present there are, 

 almost daily variations in appearance, due to causes which 

 cannot easily be overcome, such as weather, age of the trees 

 tapped, and the bringing of new trees into bearing, all of 

 which ati'ect the colour and clearness of the dried rubber. 

 The <liscoloration is due to oxidation of soluble organic bodies 

 in the latex water. Tins oxidation is produced by the action 

 of an enzyme or chemical agent causing fermentation, and 

 the process is intensitied by a warm tenijierature and 

 exjiosure to the air. 



Thorough washing of tlie freshly coagulated caoutchouc 

 will remove much of the soluble matter and also theeuzyme, but 

 it is difficult or impossible t<i remove it all, and other means 

 have to be adopted to prevent the darkening on drying which 

 almost invariably occurs. This is done by destroying the 

 enzyme by means of heat before oxidation occurs, with the 

 result that ruldjer dries <if a clear pale yellow colour, and of 

 perfect uniformity from day to day. 



The heating can be done in either of the following ways 

 before or after coagulation : — 



1. By pa.ssing steam into the bulked latex until the 

 temperature reaches SO" (_'. or 1G7" F, and maintaining this 

 temperature for fifteen minutes or longer, according to the 

 thickness of the rubber. 



2. By immersing the biscuits or .sheets, etc., in water of 

 the temperature mentioned for scmie minutes immediately 

 after passing through the rolling machine ; the rubber should 

 then be re-rolled to the requisite thiiuiess, and immersed again 

 for a shorter time to ensure destruction of the enzyme. 



3. Hot water can be employed in the washing machine, 

 and if neces.sary steam-heated rollers as well. 



Heating during the process of coagulation most nearly 

 resembles the method of making hard Para, but the other 

 methods give excellent results. 



To insure the best j)roduct, cleanliness in all stages of 

 collecting and manufacture is essential, and if the loss I'll 

 value from want of simple precautions in the preparation was 

 nK)re fully realized on rubber estate.?, much greater care 

 would be exercised. .Many samples of excellent rubber 

 apjiear on the London market, but from want of uniformity, 

 and perhaps the jiresence r)f some slight impurity, the price 

 lealized is lower than it would otherwise be. 



Rubber made by this [)rocess has already been s(jld on 

 the market, and the pi ice realized was about 4'/. per It), over 

 that commanded by ordinary good biscuits, whi<-h indicates 

 that the process can be successfully ajjplied on the estate. 

 It still remains to be [jroved whether the rubber is stronger 

 than that manufactured by the ordinary method, and Messrs. 

 Gow, Wilson, A Stanton, Ltd., rubber brokers of London, 

 are now having the product tested l:>y manufacturers to 

 determine this point. As the process resembles in .some 

 points the manufacture of tine hard Para, there is reason to 

 expect some imjirovement in the physical properties in 

 addition to the other advantages obtained. 



