

THE INDIA RUBBER WORLD 



[June 1, 1915. 



THE COLOR OF RUBBER. 



Whil urposes tin i loi oi crude rubber is of no 



, lored rubber is in general more appreciated 



nand .1 somewhat higher price tha 



dark colored. This partiallj rom the purity and othei 



qualities of the rubber beii ed from its color. In any ia>i-, 



ii i- of interest to consider the factors upon which thi color oi 



■ ilds. 



In tin- connection it -h mid lie noted that in most cases freshly 



ulated rubber, -till saturated with water, has a pure white 



which it keeps as long .1- ii retains the moisture. Thus 



balls of rubber kept under watci to which formaline ha- been 



r to prevent decomposition, after some months 



retain a white color. The same may he said ol large balls, 



which only dry graduallj from the outside and ret. on lor a 



long time their internal moisture and whiteness. 



\< Professor Zimmermann remark-, in his work upon Manihot, 

 ■',t i- not infrequentlj found that the somewhat yellowish tinged 

 lati •- of the Manihot Glazio'Ai produces a yellowish tinged rub- 

 ber, while the latex of Manihot Piaiihycnsis has a 1 all times an 

 intense yellow tinge and produces rubber of ,1 golden or brownish 

 yellow color.' 



It may. however, lie observed that even when the latex is pure 

 white it becomes se\eral -hade- darker in .Irving, ranging bi 

 tween light yellow, brownish yellow, dark brown, almost dark. 



In general th.- darkening of the rubber is caused by sub- 

 Stances already present in the latex, which become dark through 

 oxidation. Thi- may- he regarded a- a natural darkening. 1 hi 

 the other hand, substances added during or after coagulation 

 may influence the color of the rubber. Specks of different colors 

 may also he produced in drying, by bacteria and other causes. 



PLANTATION PROSPECTS FOR YOUNG MEN. 



A daily published in the Far East warns the young men of 

 In laud and other countries against viewing the possibilities 

 for lucrative employment on eastern plantations with too much 

 optimism mile-- they are specially qualified for plantation serv- 

 ice. It scents that a good many young men have left England 

 Foi Malaya expecting to drop into plea-ant managerial positions 



with salaries of $5,000 a year, and more or less luxurious quar- 

 ters 



When the plantation rubber boom was on there wa- such a 

 demand for plantation managers and assistants that a great 

 number of young men who went to the Far Hast without any 

 special qualifications obtained line positions. Hut plantation 

 onditions havi I ii have been reduced and genuine 



qualifications are now expected. Assistants are generallj em 

 ployed in supervising laborers, and consequently they are ex- 

 pected to know at least one of the several languages in use 

 among the coolies Thej are expected to study economical 

 working and apply it. and they must know how to handle men. 

 The cost of living has become very high in Malaya, and salaries 

 at the start are small, new men being looked upon as learners. 

 Generally speaking, the present is not a good time to obtain ap- 

 pointments on Eastern plantations. 



EFFECTS OF COAGULATION ON QUALITY OF RUBBER. 



It has been remarked that the question of the effects oi 

 agulation on the quality of rubber has not been fully treated in 

 technical literature. That such lias been the case is attributed 

 to the lack of methods for expressing in figures the technical 

 value of crude rubber. The theory ha- been generally accepted 

 that the best method of coagulation is that which produces an 

 article with a minimum percentage of substances other than rub- 

 ber, tin process being one in which strongly acting chemicals 

 and high temperatures, likely to injure the crude product, will 

 be av 



Tests bj Schidrowitz and Kaye of Kickxia elastica showed 

 that the percentagi ii resin in dry rubber varied between 5.30 

 and 7.X2 per cent., while pressing in conjunction with a solvent 

 reduced the proportion to 1.74 per cent. A high percentage of 

 resin (876 per cent i wa- found to exist with formaldehyde. 

 Other tests by the same experts showed that different methods 

 ul .Hon exercised an influence upon the mechanical prop- 

 erties of the rubber. 



In a series of tests Beadle and Steven- determined compara- 

 tive percentage of acids in Brazilian ani ion rubber, with 

 the fi 'Ik iw ing r< -ul' - 



Acid. 



Wild Para rubber per cent 0.120—0.168 



I 'latitat ion sheets 0.150—0.292 



Plantation crepe 0.017—0.120 



idrowitz attache- importance to the proportion of acid dur- 

 ing coagulation, a- with a low acid percentage onlj agglutina- 

 tion ensues, while too much acid, by destroying the network of 

 it- texture, would make the rubber bard and brittle. 



THE TACKINESS OF RUBBER. 

 Sometimes, in course of transportation or in storage, crude 

 ruhlier becomes "tacky," thus losing its elasticity and nerve. 

 Ibis phenomenon has often been attributed to the action of 

 microbes, but a French scientist — M. Bertrand — attributes this al- 

 teration or decomposition of crude rubber to the action of 

 physico-chemical agents. He states that when rubber becomes 

 "tacky" it is due to a molecular transformation. Exhaustive ex- 

 periments made by I'". Ileim and R. Marquis confirm Bertrand's 

 views, for they state, in giving an account of their experiments, 

 first, that the turning of crude rubber into a pitchy, tacky mass 

 is due to the absorption by the rubber of the oxygen of the air, 

 this absorption being favored by a rise in temperature; secondly. 

 that a small quantity of oxygen is sufficient to decompose a large 

 quantity of rubber, and thirdly, that smoking after coagulation 

 preserves rubber from becoming tacky, at least under the con- 

 ditions present during their experiments. Air is therefore the 

 enemy of crude rubber, which, in order to keep, must be pre- 

 served from it. The action of smoke is to cover the crude rub- 

 ber with a coating that preserves it from air and therefore for- 

 maldehyde and creosote are not really the preserving factors of 

 the smoking treatment of rubber. 



A NEW RUBBER- SMOKING INVENTION. 

 \ -nil-lance ha- been invented in Ceylon for the production of 

 a smoke for the curing of rubber, the inventor of winch describes 

 it as f< dk >W5 : 



"This invention is a composition consisting of the pith and 

 short fibres of th,- cocoanut husk ground to a coarse powder. To 

 tin- 1- added crude petroleum. The whole is then thoroughly 

 mixed and subjected to a pressure of from 20 to 80 tons. For 

 light!) smoking the rubber, the crude petroleum may he left out oi 

 the mixture, but to obtain a very good result the mixture should 

 preferably be in the following proportions: — Ground cocoanut 

 fibre and pith 100 parts. Crude petroleum from 2 to 7 parts 

 according to shade of rubber required. When the composition is 

 ready for use, it can he burnt in any ordinary tire place either in 

 compressed block or by being broken into little pieces, 

 • ilint in any way reducing the quantity of smoke produced. 

 Ihe advantages of this invention are that it will burn without any 

 t- nible anil will produce a large quantity of smoke without flame 

 at a v en small Ci ist 



MOTOR TRUCKS IN CEYLON 



There are now 100 commercial motor vehicles in use in Ceylon, 

 and it is expected that within 6,000 bullock carts 



still ii will be replaced by rubber-tired motor trucks. 



The duty on exports from Mexico of the guayule plant, either 

 in the natural state or -round, as fixed on October 19. 1914. by 

 General ( arranza, in bis character as provisional President de 

 facto, i- $15 per 1,000 kilos (1 ton I gross. 



