336 



THE INDIA RUBBER WORLD 



[July 



1905- 



been sent to the Mexico Museum as a rubber producing plant. 



Although it was formerly contended that the Guayule plant 

 was to be found throughout almost the entire north and north- 

 east of Mexico, this supposition has been proven to be un- 

 founded. Still, there seems to be enough material at hand to 

 supply the demand of a considerable number of good sized 

 rubber works. 



Besides some smaller districts in Chihuahua, the northern 

 parts of the states of Zacatecas and San Luis Potosi, the east- 

 ern part of Durango, and especially the southern districts of 

 Coahuila, appear to offer a profitable field for the working of 

 the Guayule plant. It is said that smaller places of supply, al- 

 though sometimes at considerable distances from each other, 

 extend from the south of Coahuila to the state of Chihuahua 

 (where the plant has hitherto been found only near Santa Ros- 

 alia and Jimenez), and that the plant is sporadically found as 

 far as New Mexico and Arizona. The " Biologia Centrali- 

 Americana " states that the Guayule is likewise indigenous to 

 southern Texas. 



The eastern boundary of its territory is formed in San Luis 

 Potosi and southern Coahuila by the foothills of the Sierra Ma- 

 dre Oriental. The western boundary in Zacatecas and Durango 

 would scarcely exceed a strip of an average width of about 100 

 kilometers, running parallel with the Mexican Central railway. 

 On the line of the International railway, in a westerly direc- 

 tion, a few isolated p'ants only are found above Pasaje. The 

 plant known as Guayule on the lower Rio Grande and in Nuevo 

 Leon, as well as in the district of Monclava (Coahuila), is 

 neither by its qualities, nor by the territory in which it occurs, 

 in the least similar to the Parthenium argentatutn. 



The existence o( the Guayule in the southern part of the 

 Mexican highlands, between Puebla and Tehuacan, has not as 

 yet been proved. Assertions made in this regard have been 

 found to be merely suppositions and were not confirmed by the 

 investigations hitherto made. The same appears to be the case 

 with the reputed Guayule of Central America and Venezuela. 



Concerning the elevation on which the Guayule is found, its 

 chief territory may be placed between the altitudes of 900 and 

 1700 meters [ = 3000 to 5600 feet]. The largest supply within 

 this zone is not as often found on the plateaus as on the inclines 

 and hills, and more specially on the low foothills of the larger 

 mountain chains, the soil preferred by the plant being mostly 

 very dry and often rocky, with a large percentage of lime in its 

 composition. 



The supply of Guayule in its territory is very unevenly dis- 

 tributed. In most parts the plants are isolated, growing some- 

 times in large and oftentimes in small numbers among the 

 other plants of these mountain inclines, rich in lime. At rare 

 intervals small spaces are found, where it predominates among 

 the llora of the chaparrales. 



An estimate of the average supply per hectare is very diffi- 

 cult to make, both on account of the uneven distribution of the 

 plant and of the great differences in the size of the individual 

 plants. In favorable territory I have on several occasions 

 counted 30 to 40 plants on an area of 100 square meters, which 

 would mean a total supply of 3000 to 4000 Guayule plants per 

 hectare [ = 1215 per acre]. The differences in size and weight 

 are so great that in places where the plants are small and grow 

 close together 10 plants have a weight of only one kilogram 

 [ = 2! pounds], while in the best territories some of the trees 

 weigh as much as 3 kilograms each. The average weight will 

 probably not exceed 500 grams [ = 1,',, pound] per plant. 



Estimates of the Guayule supply in large areas vary from 500 

 to 800 kilograms per hectare, but the distance between the dif- 

 ferent places where the plants are found are often considerable. 



and must be taken into consideration. The territory contain- 

 ing the more important places of supply, include a total area of 

 about 75,000 square kilometers [=about 29,000 square miles]. 



The Guayule, the only rubber producing plant belonging to 

 the order of the Composita: known at the present time, is dis- 

 tinguished from the other rubber producing Euf>horbiaceir, Mor- 

 (ececr. Apocynaceic, etc., by the peculiarity of its bark, which con- 

 tains no milk sap. It appears that the rubber of the Guayule 

 is dissolved in the sap of the cellular tissue, not only of the 

 bark, but likewise of the wood. Only the shoots bearing the 

 leaves and blossoms seem to contain no rubber, as experiments 

 show that no rubber can be obtained from them by chewing 

 them, while rubber may be obtained in this way from the other 

 parts of the plant. Although considerably less rubber is pro- 

 duced from the wood than from the bark, the rubber contained 

 in the wood is purer, and consequently lighter in color (amber 

 yellow). 



The relation between the amount of rubber contained in the 

 bark and that found in the wood of the branches is approxi- 

 mately that of 7 to 2. The bark, moreover, contains aromatic 

 substances of a balsamic character, and especially in separate 

 ducts a gumlike product of degradation, which shows itself in 

 drops on the surface whenever the plant has suffered an injury. 

 The substance, which Is similar to gum arabic and light in color, 

 has hitherto been the cause of the stickiness of the Guayule 

 rubber, and, consequently of its low market value. 



.As the crude material is difficult to break up or cut when 

 fresh, it is worked after having been more or less thoroughly 

 dried. In the dry climate of the Guayule districts it is usually 

 sufficient to expose the gathered plants for a few days to the 

 air, so as to prepare them for working. Various tests of the 

 weight of dried plants showed that 100 parts were made up of 

 47 per cent, of wood and 44 >^ per cent, of bark, while there re- 

 mained only 8^ per cent, of leaves and of the shoots of the 

 previous year, a part of these being lost during transportation. 



The price of dried Guayule plants, including freight charges, 

 has hitherto been quoted at 15 pesos. At the present time, 

 when several competing enterprises are about to acquire a 

 larger supply of plants the price has risen to 30 and even to 40 

 pesos per ton, according to the distance between the places of 

 origin and the stations or works. 



For transportation by rail the Guayule is usually packed in 



pressed bales. The old method of shipping it in bulk had the 



disadvantage of requiring more labor. Besides, parts of it were 



often stolen at the stations, the people taking it for use as fuel. 



EDITORIAL NOTE. 



In the exhibits from Mexico at the Philadelphia Centennial Exhibition 

 of 1876, the display made by the state of Durango included a specimen 

 of good rubber stated to have been produced from a native plant of the 

 genus Cynanchum of the natural order Asclepiadea, according to St nor 

 Fernando Altimarano, of Mexico city, to whom the plant had been sent 

 for study. This appears to have been the first rubber from that region 

 seen in the United States. In 1888 Mr. John H. Cheever, the founder 

 and then treasurer of the New York Belting and Packing Co., imported 

 from Hot Springs, 15 miles from Santa Rosalia, state of Chihuahua, 

 Mexico, 100,000 pounds of a shrub known locally as " hule," from which 

 the bark was removed and from the treatment of the latter a yield of rub- 

 ber was obtained equal in weight to about 18 per cent., which Mr. 

 Cheever regarded as equal to the best grade of "Centrals" in the market. 

 On account of the freight charges the cost of the rubber produced by Mr. 

 Cheever was equal to the current selling price of good " Centrals." and 

 he was not interested in further experiments. This was probably the 

 most extensive operation up to that time in producing rubber from the 

 plant now known so widely as " Guayule." A report on Mr. Cheever's 

 experiments appeared in The India Rubber World, April 10, 1895 

 [page iggj. 



