January I, 1913.] 



THE INDIA RUBBER WORLD 



191 



all stumps of timber, is of paramount importance, for the expedi- 

 tious and economical accomplishment of which work there is in 

 dynamite an adequate material. According to the "Home and 

 Colonial Mail" experiments are becoming quite popular in South 

 Africa of pl(>ui>bing by dynamite. 



All tlie leading papers in the rubber producing world, as well 

 as those devoted to planting interests elsewhere, recommend atten- 

 tion to the use of dynamite for estate work. Its employment 

 especially appeals to the author, in connection with Latin America 

 where the transport of even the lightest make of ploughs is diffi- 

 cult, costly and often impossible. In lighting locusts and various 

 other pests, organized explosions tend to their reduction at all 

 stages, whetlier in the soil or as gruljs flying over it. 



Tlie author quotes a letter to the "Times of Ceylon" from Kal- 

 kudah in the Eastern Province of the island, referring to the ad- 

 vantages of using dynamite for breaking through the slabs of coral 

 which run from the coast to one and a half miles inland. This 

 coral runs from 2 to 9 feet below the surface, and measures in 

 some places from 18 to 24 inches in thickness. 



In conclusion the author remarks that there is no doubt ex- 

 plosives have not only come to stay as a necessary auxiliary to 

 modern agricultural science, but that their use will extend on all 

 sides until they occupy a prominent position in rubber planting 

 and other branrbes. 



POSSIBLE RUBBER PRODUCERS IN THE TEM- 

 PERATE ZONE. (Abstract.) 



liy Cluulcs P. Fox. 



AV/IIILE llie production of rubber in the temperate zone has 

 *' been regarded as possible, its probabiUties are remote 

 and dependent on many conditions. Some of these are : De- 

 mand ; cost of production : grade of product ; influence of sup- 

 plies of natural and plantation rubber; and the ever recurring 

 spectre of synthetic rubber. 



From his investigations extending over fifteen years, the 

 author has found several rubber producing plants suitable for 

 the various sections of the temperate zone. Among foreign 

 plants were Atractylis and Eucoinmia, the most interesting 

 specimen being the Eucoinmia nhnoldes, or "Chinese Rubber 

 Tree." said to be hardy in New England. This source of rubber 

 was found only suitable for ornamental forestry. Of native 

 plants, those of possible value as rubber producers are members 

 of the Asctefiadaceae, Apocynaceae and Compositac families. 



Of the true milkweeds, only one is of any importance, 

 Asclepias Cornuti, which is very abundant and contains a quan- 

 tity of milky juice producing 3 per cent, of fair grade rubber. 

 The cost of collecting the latex is, however, prohibitory. The 

 common Indian hemp, Apocynnin Canuabium is less abundant 

 than milkweed and produces less latex, but the quality of the 

 rubber is better. The third native group named, that of the 

 Coinpositac. include Soitchus or Sow-thistle, producing an ex- 

 cellent grade of rubber, which- is the subject of a German 

 patent of 1885. It grows on a dry barren soil. 



Two species of wild lettuce, Lactuca Canadensis and Lactuca 

 virosa, both produce a thick latex containing rubber. Another 

 promising plant of the arid region is "Strockle's Rubber Bush," 

 a robust member of the Conipositac family. 



As to the arid section of the Temperate Zone, it is amply 

 provided with guayule (Parthenium Argentatum} pingue, grease- 

 wood and Candelillia. It is stated that since the first of these 

 can be successfully grown in Mexico, it should thrive equally well 

 in the Southwest of the United States. Pingue (Aclinella 

 Richardsonii), with less rubber than guayule. has superior ad- 

 vantages in other respects. 



Nevada greasewood contains rubber, as shown by Ellis and 

 Warner's patents of 1902. A large amount of this plant is 

 reported to be available. 



In North Mexico and the Big Bend country of Texas there 

 is an immense growth of Candelillia, producing rubber and 

 wax, the latter being used in making hard rubber. 



Some 15 years ago rubber growing was attempted wiili 

 Ficus clastica in Key West. Florida, but proved a failure, the 

 conditions being too dry and the soil shallow. 



The same tree has grown to a large size in the deep, fertile 

 and moist soil near Miami. Rubber as good as the Mexican 

 "Amate" rubber has been grown on a small scale at Palm 

 Beach. Florida, with its large available area of soil suitable 

 in character, seems to offer specially good prospects for rubber 

 cultivation. 



While the other plants named are of interest from a botanical 

 point of view, the author considers that only two, guayule and 

 I)ingue, contain enough rubber to insure profitable working. It 

 is for experimental stations to continue the work of developing 

 the others. 



THE PLASTOMETER, A RUBBER TESTING INSTRU- 

 MENT (.Ibstracl). 



By B. Denver Coppa:.;e (IVihnington, Del.) 



THIS instrument, designed for the use of its manufacturers, 

 the Pussy and Jones Co. of Wilmington, Delaware, is 

 intended to define the plasticity or density of the rubber 

 covered rolls used in paper manufacture. These rolls have 

 to be selected suitable to the paper to be made. 



Since the adoption of this instrument tliere is no uncertainty 

 as to the conformity in plasticity of the rolls with the samples 

 chosen. Plasticity also indirectly indicates elasticity, softness 

 and hardness, density, resilience, etc. 



In the plastometer a weight is supported upon a sphere, the 

 penetration of which into the material at the expiration of 

 one minute can be determined. For instance, most grades of 

 commercial rubber may be tested with a hardened steel ball 

 ?4 inch in diameter and a weight of one kilogram. The 

 penetration or indentation of such a ball is indicated to 

 1/100 of a millimeter. The softer materials would require a 

 larger ball or less weights, or both. The harder materials 

 would require a smaller ball or more weight, or both. Certain 

 very hard materials would possibly require a longer applica- 

 tion of the weight than one minute, while certain very soft 

 materials would require less than a minute to obtain satis- 

 factory indications. 



The possibility is discussed of utilizing the plastometer for 

 establishing a standard scale of qualities for rubber and for 

 the determination of raw rubber values. The plastometer is 

 used by many leading rubber manufacturers in this country, 

 and by users of paper making machinery at home and abroad. 

 It has so far been developed by a buyer of rubber, while its 

 further development for the benefit of that trade will un- 

 doubtedly depend upon the engineers and chemists directly 

 connected therewith. 



THE VARIOUS MANIHOTS PRODUCING RUBBER IN 



THE CENTRAL STATES OF BRAZIL (Abstract). 



By Dr. J. Santiago Cardivcll-Quinn. 



pvR. CARDWELL-QUINN has contributed an interesting 

 '-^ and exhaustive treatise on this subject, but he was not 

 able to submit it in time to be read at the conference ; and 

 in fact it was not received by the secretary of the conference 

 until a few days ago. and too late to make it possible to 

 present an adequate abstract of it at this time. It will be 

 reproduced in full in a later issue, and w-ill prove a valuable 

 contribution of the literature of the Manihots. 



