August 1, 1914.] 



THE INDIA RUBBER WORLD 



601 



much greater than is that of gasolene or ether solutions. 

 Especially in the case of the plantation rubber is a marked dif- 

 ference observable between the viscosity in benzol and the 

 viscosity in gasolene. In comparing the viscosities of different 

 rubbers in the same solvent, it is necessary tc make a correction 

 for the amount of resin present in the rubbers. On making 

 this correction, viscosity curves for Fine Para and Castilloa 

 practically coincide. Furthermore, the lowering of the vis- 

 cosity due to washing the rubber on the mill in a stream of 

 cold water is greater in the case of Fine Para than in the case 

 of Castilloa. For connecting the viscosity of solutions with 

 the concentration, the author suggests the use of the follow- 

 ing logaritlimic equation: 



, = K' 

 where ix := viscosity at cunccntratiim X, .\ = concentration, 

 and K = constant. 



By plotting the logarithmic viscosity against the concen- 

 tration, straight lines were obtained in the case of the rubbers 

 e.xamined and the author suggests that the inclination of 

 these lines with the abscissa would seem to be the simplest 

 way of numerically comparing the viscosity of rubber solu- 

 tions. ^ 



Both heat and liwlit lining about a lowering of tlie viscosity 

 of rubber solutions. At high temperatures the effect of light 

 appears to be less marked than that of the heat. In fact, the 

 effect of light began to make itself felt only after two hours 

 under the simultaneous action of heat. It w-as observed that 

 heat alone, in the absence of air, caused decrease of viscositj'. 

 The action of heat, therefore, is to decrease the viscosity of 

 rubber solutions, apart from any oxidation which the rubber 

 may undergo. The rate of diminution of the viscosity varies 

 with the time of heating, being greatest at the commence- 

 ment. 



Kxperiinents were also carried out to determine tlie cliange 

 in viscosity of Plantation Para in different solvents when 

 heated to 80° C. The change is more marked in the case of 

 xylol solutions than in the case of benzol and toluol solutions. 

 In purified toluol, the diminution is less than in commercial 

 toluol. .\ similar difference is observed between solutions in 

 pure benzol and solutions in 90 per cent, benzol. The effect 

 of the addition of small quantities of the usual impurities in 

 benzol (carbon disulphide, thiophene and xylol) was de- 

 termined. Only xylol caused an increased diminution in vis- 

 cosity. A rubber solution of benzol containing 0.5 per cent, 

 xylol decreased in viscosity much more rapidly than did the 

 pure benzol solution. In order to determine the decrease in 

 viscosity of different rubbers under the action of heat, solu- 

 tions of equal viscosity of the different rubbers were taken 

 and their viscosity redetermined after the heat treatment. 

 It was found that the percentage decrease of the Hevca rub- 

 bers was greater than that of the Fuiitumia, Castilloa, and 

 Ceara rubbers. The author explains tlie decreases in vis- 

 cosity as being due to a de-aggregation or depolynierization 

 of the rubber molecules. 



VANADIUM AND TUNGSTEN AS COMPOUNDING INGREDIENTS, 



Chemical compounds derived from the commonly occurring 

 minerals have been used in rubber compounding since the 

 beginning of that art. and today when the writing of recipes 

 is getting to be a science, the original line of mineral substances 

 is still being used. 



Since our manufacturers have enlisted the services of re- 

 search chemists they have, however, added to the number of 

 suitable mineral fillers. These indefatigable workers have ex- 

 plored the domain of "rare" metals and the results of their 

 labors are being given to the consumer in the form of "long 

 life" rubber goods. ■^■■i, yl>,. 



.■\t Primes, Pennsylvania. Walter M. Stein has been conducting 



experiments with the aid of Vanadium Pentoxide (V-2, 0-5) 

 and Tungsten Trioxide (Wo. 0-3). The preliminary work on 

 these oxides seems to indicate that they are useful as "tough- 

 ening agents" and as "accelerators." With this as a beginning 

 may we not hope to see a "Hole-Proof Gum Shoe" or a "Knotair 

 I'irehose" ere long? The preliminary reports state that less than 

 f\\c per cent, of either oxide will influence the properties of 

 the compound to a marked extent. In fact it may be necessary 

 to use the oxides in Hahnemannian doses m order to obtain 

 the maximum toughness in the compound. 



Surely the Automobile Set will wish Mr. Stein unlimited 

 success in this new application of Vanadium and Tungsten 

 compounds, for the selfsame oxides are even now being suc- 

 cessfully used for toughening no less a thing than steel! 



INTERESTING LETTERS FROM OUR READERS. 



WILLING OTHERS SHOULD GET THE SYNTHETIC PROflTS. 



■ I 'O THE Editor of The India RunsER World, Dear Sir: 

 •^ Your interesting editorial on the latest synthetic rubber 

 ( wliich includes resins in its composition ) remainds one of 

 the inventor who produced synthetic milk so perfect that cow 

 hairs had to be strained out of it. If rubber can be produced 

 at eight cents a pound, the benefit ought to be for the whole race 

 instead of the fortunate few who manage to be the first to get 

 to the window with their million dollars to buy the stock of the 

 company. The capitalization ought to be a hundred million at 

 least in- order to give a hungry and clamorous public a chance 

 to get in on the ground floor. That the public right may be 

 maintained there ought to be a federal law by which the owners 

 of great secrets of this character should be compelled to per- 

 form their magic arts in the government laboratories at Wash- 

 ington before they sell any securities to the public. They should 

 have every help and facility, and if they can make rubber out of 

 sawdust or frozen potatoes the certificate of government chem- 

 ists that they actually had done the thing would well repay them 

 for their time and trouble. 



If, on the other hand, they need eight pounds of sawdust, eight 

 pounds of tree rubber and four pounds of frozen potatoes for 

 every eight pounds of synthetic rubber produced, it would be 

 shown that tlie latter was not manufactured so economically as 

 to warrant the expectation of large dividends on extensive cap- 

 italization, and the promoters would be advised to form a close 

 corporation for the exploitation of their invention and especially 

 not to use the United States mails in connection W'ith their 

 stock-selling until they were able to reduce the amount of tree 

 rubljcr going into their synthetic product. Meantime, I shall not 

 join the rush for the new securities. I am not selfish and do not 

 wish to be the envv of mv fellow-men. Altruist. 



protect plantation RUBBER PROM SPLINTERS BY WRAPPING 

 IN GLAZED SHEETING. 



npO THE Editor of The Indi.\ Rubber World, Dear Sir: 

 ^ Mr. H. W. French's timely letter in the June number of 

 The Indi.\ Rubber World re wood splinters reminds me of the 

 remedy suggested by a brilliant Boston superintendent and chem-' 

 ist, namely : Before packing plantation rubber in the East it 

 should be wrapped in glazed sheeting such as is used in keeping 

 uncured tape from sticking together. This is said to come one 

 yard wide, and moreover is cheap. 

 Boston. QuiNCY Tucker. 



Should be on every rubber man's desk — Crude Rubber and 

 Compounding Ingredients; Rubber Country of the .\mazon : 

 Rubber Trade Directorv of the World. 



