300 



THE INDIA RUBBER WORLD 



[July i, 1907. 



RUBBER FROM A TUBER AT LAST. 



AFLAN 1' tounii in Portuguese West Africa, and not hitherto 

 known to science as a source of rubber, is the subject 

 of a recent report by Professor Carlos Eugenio de Mello 

 Geraldes, of the agronomical institute at Lisbon. The plant is 

 referred to as flourishing in the sandy, treeless plateaus around 

 Bailundo and Bihe, inland from the seaport of Benguela, and 

 lying particularly between the Kwanza and Zambesi rivers. This 

 region was described in The India Rubber World May i, 1903 

 (page 26) as the source of large quantities of "root rubber," 

 which grade has been exported extensively from Benguela. 



though the plant now 

 described has no rela- 

 tion to those producing 

 the class of rubber here 

 referred to. It is 

 ascribed by Professor J. 

 Henriques, of Coimbra, 

 to the natural order 

 Asclcl'iadaccic, while the 

 Landol/'hia Tholl o n i i 

 and other "root rubber" 

 species belong to the 

 Al>ocyiiaccc€. 



The new plant, known 

 by the natives in dif- 

 ferent localities as 

 "ekanda" and "mari- 

 anga." is a stemless 

 biennial plant, with a 

 fleshy yellow tuberous 

 root, sometimes turnip 

 shaped, but most fre- 

 quently in form resem- 

 bling a flattened sphere, 

 the entire substance of 

 which is permeated with 

 lactiferous ducts. The 

 plant ends at the top 

 in a simple or bifurcated prolongation or pseudo stem, 2 to 4 

 inches in length. The leaves are dark green, in two to five 

 pairs, forming a rosette near the earth ; they are simple, oval 

 shaped, with a small point, and slightly hairy. The feather- 

 like veins are light green in the young leaf, but turn violet red 

 shortly before blossoming. The blossoms are five fold, small, 

 violet red, and mostly sterile. In form they suggest a bunch 

 of grapes, and are enclosed in a sheath prior to opening. The 

 fruit is a spindle-shaped bag capsule, sometimes as long as four 

 inches, and containing up to 50 seeds. 



Rubber has been obtained from the "ekanda"' tubers by vari- 

 ous crude experimental processes, but chiefly by siicing them 

 and applying pressure. The latex is referred to as coagulating 

 with the application of alcohol, but not of alum. It has been 

 suggested that by means of centrifugalization of the expressed 

 juices a creamed latex could be obtained which would yield a 

 purer rubber than has yet resulted from the experiments. 

 Tubers two years oM are referred as attaining a diameter of 

 5^ inches and a weight of i 1-3 pounds, and a rubber yield of 

 \4 per cent, of the total weight resulted from crude processes. 

 Professor Geraldes, who regards the plant as adapted to culti- 

 vation, has figured out estimates of yield and profits, but these 

 must be regarded as yet as hypothetical, and need not be re- 

 peated at this time. It may be mentioned, however, that he 

 regards as possible a product of 200 kilograms of rubber per 

 hectare [=iSS pounds per acre] at the end of two years. But 

 his estimate of the value of the rubber (about $1.28 per pound) 

 is clearly too high for the quality likely to be yielded from such 

 a source. 



The term "potato rubber," formerly sometimes used in the 

 trade, did not, as some supposed, relate to rubber obtained from 

 a sort of tuber, but to the appearance of the small balls in which 

 certain rubbers came to market, particularly "almeidina," a cheap 

 gum exported in small quantities from Portuguese W^est -Africa, 

 but having no relation whatever to the "ekanda" product. 



The "Ek.\nd.\" Pl.vnt. 



t>er prod( 

 Portuguese West Africa. ] 



[A newh- discovered rubber producer 

 Po 



PROGRESS IN INSULATION. 



I 



HIGH TENSION EXFEBIMENTS AT WTT.AW. 

 C OME high te:ision experiments of much interest were made at 

 *~^ the Milan exposition on cables manufactured by Pirelli & 

 Co. These experiments were made a number of times ; among 

 others, some before the electrical congress and once before the 

 King of Italy. The cables tested were insulated with india-rub- 

 ber. Though the company manufacture paper insulated cables 

 largely, they believe that rubber insulation is necessary for very 

 high tension work, for reasons demonstrated in the lecture by 

 their electrical engineer, Mr. E. Jona, at the St. Louis Electrical 

 Congress. The Pirelli firm have built a cable for working at a 

 voltage of 100.000, and none of the lengths tested has broken 

 down under 200.000 volts. There is no record of such high ten- 

 sions having been reached previously. Mr. Jona has described 

 these cable tests in The Electrician (London). 



Mr. Jona describes also some stranded cables made by Messrs. 

 Pirelli. The stranded conductor is sheathed in a lead tube and 

 subsequently insulated by several layers of vulcanized rubber, up 

 to a total thickness of 5.5 millimeters. Then follows a coating of 

 1.2 millimeters of gutta-percha, to insure absolute imperviousness 

 to water. The core is then served with tarred jute and armored 

 with 18 steel wires 3 millimeters in diameter. Three such cables 

 were used in Italy to form a three phase line. In experiments 

 made with such cable at Milan, designed for use on a 6o,ooo-volt 

 line, it was tested up to 160,000 volts. 



BI*R VOLTAGE trilDEEGROUNI) CABLES. 



There seems to be a demand, says the Electrical Review (New 

 York) for cables which can be used safely on a 44.000-volt sys- 

 tem underground. At present the high tension apparatus of a 

 city system is capable of operating at a considerably higher volt- 

 age than that employed, with the exception of the cables, and the 

 Reviezv is of the opinion that when cables for these higher pres- 

 sures are demanded they will be forthcoming. 



"If 44.000 volts be adopted for underground transmission lines, 

 and it be found successful, it would not be surprising to have 

 even higher voltages tried. Such a system is coming very close 

 to the voltages now employed on the longest overhead transmis- 

 sion systems. These generally I'e between 50.000 and 60.OC0, the 

 latter figure as the upper limit, set. not by the weakness of the 

 electrical apparatus, but because above this point the losses from 

 the overhead wire increase rapidly. It is possible that some such 

 limitation will be found for underground cables, yet if trans- 

 former windings operate satisfactorily at 80,000 volts or more the 

 limiting consideration may be merely one of cost. The insulation 

 thought to promise best for such cables is one consisting of cloth 

 tape properly impregnated with some good compound. Rubber 

 will hardly be used until some way of preventing the deleterious 

 efltect of high tension discharges has been devised. This is for- 

 tunate, in a way, since our rubber resources are already taxed to 

 the utmost to supply the necessary quantity of material for in- 

 sulating low potential wires." 



Hot water bottles may be provided with an electric heating 

 device, by means of which the water may be kept heated and 

 at a constant even temperature as long as may be desired. This 

 obviates the necessity of constantly refilling the bag with hot 

 water. The electric heater may be attached to a water bottle 

 stopper of the ordinary type, and connected by a short wire to an 

 electric light socket. Such a device is the "Standard" water 

 bottle heater sold by C. J. Bailey & Co., Boston. 



