January 1. 1913.] 



THE INDIA RUBBER WORLD 



183 



petus about three years ago when two German chemists, 

 Hofmann and Harries, working independently, simultane- 

 ously discovered products that gave the chemical reaction 

 of rubber and possessed certain physical resemblances to the 

 natural product. The recent forming of stock companies to 

 place synthetic rubber on the market has attracted much 

 attention to the subject on the part of the press and the 

 public generally. While the author greatly admires the tine 

 work of the chemists in accomplishing the results attained, 

 he deplores the attempt to make the public think that syn- 

 thetic rubber is an immediate commercial probability. 



He cites the comparison synthetic enthusiasts make be- 

 tween the success in synthetic indigo and the probable suc- 

 cess in synthetic rubber. In his opinion, the two problems 

 have little in common, as indigo is an article of absolutely 

 deiinite characteristics and properties, and moreover, the 

 investigator can tell in a few moments whether the product 

 he has obtained is indigo or not, a condition totally differing 

 from the conditions under which synthetic rubber is made. 

 Synthetic rubber is obtained by the polymerization of iso- 

 prene. This the author defines as a process whereby a large 

 number of small units combine to make a single large unit. 

 It is essentially a process of agglomeration. The molecules 

 of isoprene — at least a hundred of them — unite and poly- 

 merize into one single molecule of rubber, but the difficulty 

 is that it is impossible to determine how many isoprene 

 molecules are necessary to make one molecule of rubber, and 

 equally impossible to obtain any uniformity of polymeriza- 

 tion. The chemist cannot control the process. He says: 

 "With the chemical methods available to-day, it would be 

 absolutely impossible to make a product with an assured 

 uniform degree of polymerization," and without this uni- 

 formity commercial synthetic rubber is an impossibility. 



Synthetic enthusiasts also ignore a very important fact, 

 that by 1916 the plantations will be producing at least 

 100,000 tons of rubber, and that in consequence the price of 

 rubber will be much lower than at present. Plantation rub- 

 ber is even now — according to report — being produced at 

 25 cents per pound. At any rate, the large dividends of 

 many plantations show that much plantation rubber is now 

 being produced at a comoar-itively low figure, so that even 

 if synthetic rubber could now be marKetea m la.-ge quanti- 

 ties at SO cents a pound, it would soon come in competition 

 with plantation rubber that could be produced even cheaper. 

 Moreover, it will be quite possible for the plant physiologist 

 to still further increase the production of rubber plantations 

 just as he has increased the beet-sugar yield. 



Synthetic indigo was able easily to overcome competition 

 with the natural article, because natural indigo was pro- 

 duced under tlie crudest and most unintelligent methods. In 

 rubber plantations the case is entirely different as the rubber 

 planters are keenly alive to all the possibilities of scientific 

 methods of cultivation, production and preparation. Briefly. 

 the author's position is this: That, with our present chemical 

 methods it is impossible to assure a uniform synthetic prod- 

 uct, and that within the next few years plantation rubber will 

 be in a position to make a stubborn fight against any syn- 

 thetic rubber nroduct. He does not take the ground that 

 synthetic rubber will never be a commercial possibility, but 

 doubts whether anyone now in the rubber industr}' will live 

 to see synthetic rubber in successful competition with the 

 natural product. 



After the close of that exposition the author toured through 

 Ceylon, the Federated Malay States and Java, studying the prepa- 

 ration of rubber and methods of tapping. Subsequently, he made 

 many tapping experiments and reached the conclusion that the 

 best method was a combination of e.xcision and incision. 



Excision alone he believes detrimental to the tree, as the 

 coolies in their endeavor to get the maximum latex almost in- 

 evitably cut too deep, thus injuring the lactiferous tubes close to 

 the cambium. These deep wounds heal slowly, retard the growth 

 of the tree and give access to fungus. He does not consider in- 

 cision alone practical, but advocates a shallow excision combined 

 with incision made by a fine push pricker. Where the points of 

 tlie pricker are fine they may penetrate the cambium without in- 

 jury. He does not advocate broad blunt teeth. He got satisfac- 

 tory results from a push pricker with gramophone needles filed 

 flat on two sides and fitted H inch apart into a small block of 

 wood. He followed the half herring-bone system on about one- 

 third of the tree's circumference. 



THE TAPPING OF RUBBER TREES. {Abstract.) 



By R. Fytfc. 



T^HE operation called tapping is one of extreme importance and 



■^ the present methods are susceptible of marked improvement. 



This subject did not receive the consideration in the London 



Conference of 1911 that its importance warrants. 



NOTES ON THE ACCLIMATIZATION AND CULTI- 

 VATION OF THE GUAYULE (PARTHENIUM 

 ARGENTATUM— GRAY). (Abstract.) 



By Francis E. Lloyd, 

 MacDouald Professor of Botany, McGill University, Montreal. 

 IN connection with the general conditions affecting guayule 

 cultivation, the results available to the author have been from 

 plants grown at Cedros, Zacatecas, Mexico; Tucson, Arizona; 

 Stockton and Austin, Te.xas ; and Auburn, Alabama. These situ- 

 ations included the semi-arid Chihuahuan and Sonoran 

 deserts, within the former of which the guayule has its natural 

 haliitat ; the nioister climates of Eastern Alabama (with a rain- 

 fall of 45 to 55 inches), and Eastern Texas. 



Guayule is by no means uniform in structure within its natural 

 area; the variations arising being due to differences in available 

 moisture, this being in turn attributable to greater rainfall or to 

 the character of the soil. These structural differences are 

 those of relative thickness of the bark (or corte-v), which is 

 tliinner in proportion to the greater amount of water available. 

 Correlated differences are to be noted in the length of the 

 annual acciciiuno oi stem. 



In the easternmost region of the distribution area (the state of 

 Xuevo Leon) the practical extraction of crude rubber is reduced, 

 roughly speaking, to about 4 to 5 per cent, of the wild weight. 

 This does not necessarily mean that the amount of rubber, in 

 proportion to the volume of rubber-bearing tissues, is less than 

 elsewhere, but that the volume of woody tissues is greater. 

 Nevertheless such may be the case, and in view of what we know 

 about the relation of water supply to the amount of rubber 

 secreted, it is not considered improbable that the actual intracellu- 

 lar secretion in these Nuevo Leon plants is somewhat less than 

 in dryer regions. 



The well-known habitual differences between "Macho" and 

 "Embra" guayule have been attributed to racial differences, but 

 whether this is so or not, the practical distinction in Mexico is 

 marked, the former being regarded as decidedly better in rubber 

 content. The inferiority of the latter is due to the greater relative 

 volume of the woody cylinder and the relatively greater number 

 of smaller branches. 



One of the principal differences in minor details is that the 

 greater the water supply, up to the limit thus far observed, the 

 greater is the volume and hardness of fibrous or woody tissues 

 barren in rubber, the greater the irregularit>' of growth, and the 

 larger the number of smaller twigs and leaves. 



As to the tenure of life, a combination of conditions may 

 prove fatal to plants when moved to another habitat, while they 

 might successfully resist the influence of any one factor. Thus 

 guayule can withstand cold better under arid, than moist, condi- 



