December, 1909.] 



485 



Saps and Exudations. 



rubber. This article occurs in the form 

 of minute microscopic granules deposited 

 throughout the tissues of the stem, 

 branches, and roots, but especially in 

 the bark of these organs. If one will 

 take a very thin section of the stem or 

 branch and examine it under a lens, he 

 may see much of the tissue densely 

 crowded with small, dark coloured 

 granules. In these granuels, deposited 

 within the living cell, is the source of 

 the rubber, to separate Avhich requires a 

 special process. 



Methods of extraction of guayule 

 rubber differ. Some obtain the rubber 

 by trituration of the plant and a sub- 

 sequent more or less mechanical process ; 

 others by means of solvents separate 

 the gum from tissues after grinding 

 them. But the details of the process 

 are kept secret, the public not being 

 admitted to the factories, which are 

 surrounded by high walls with armed 

 guards at the gates. However, several 

 processes are described by Dr. F. 

 Altarnirauo in the Boletin de la Secretaria 

 de Fomento of Mexico. One of the 

 methods consists in first crushing the 

 plants by grinding them in a machine, 

 in which they are tumbled among hard 

 stones until thoroughly pulverized, and 

 the gummy substance collects in lumps 

 with a certain amount of woody tissue. 

 To isolate the gum, this material is then 

 boiled over steam in an iron vessel with 

 a double bottom, and the woody particles 

 afterwards strained out. After this 

 operation the mass is thrown into a 

 tank of cold water ; again it is strained 

 and boiled anew with caustic soda until 

 the woody particles are fully separated, 

 and the gum is precipitated by chloride 

 of calcium. 



The process of extraction of guayule 

 rubber involves therefore the immediate 

 destruction of the plant. The natives 

 employed to collect the plant uproot 

 them, and take no pains to spare any 

 parts. The bushes are then packed on 

 the backs of burros, and carried to some 

 place for baling and shipment. The 

 cheapness of labour makes it feasible to 

 transport the plants for considerable 

 distance by pack train or wagon. Some- 

 times the load is carried for as much as 

 forty miles from where the plant is 

 gathered to the railway station, such 

 distances usually by wagon. The cheap- 

 ness of labour makes such operations 

 profitable, the wages of a peon being 

 about thirty-seven cents a day, Mexican 

 currency. 



The manufacture of rubber from 

 guayule is an industry of only recent 

 development. The production of gum 

 from this plant has been known from 



the middle of the eighteenth century. 

 The Indians were accustomed to make 

 rubber balls by chewing out the gum 

 from the bark. If one takes a mouthful 

 of the bark and thoroughly masticates 

 it, rejecting the fibrous particles, he may 

 soon obtain a small mass of rubber the 

 size of a pea. The rubber thus obtained 

 is soft and sticky, adhering to the skin 

 as it is manipulated batween the thumb 

 and finger. 



For some time no effort was made to 

 manufacture this rubber on a large scale. 

 In 1890 a German chemist first attempted 

 to extract it in commercial quantities, 

 but a paying basis was not reached until 

 some years later. In 1905. according to 

 consular reports, the guayule rubber 

 shipment from Durango amounted to 

 $125,478. From Torreon in 1996 rubber 

 was shipped to the value of $917,571. 

 During the year ending in June, 1908, 

 there was shipped from the Durango 

 consular district alone, guayule rubber 

 to the value of two and a quarter 

 millions. Since then the business has 

 increased, and is one of Mexico's most 

 important industries at the present time. 

 Extensive tracts of land and millions of 

 capital are involved in the enterprise. 

 The Continental-Mexican Rubber Com- 

 pany of New York, in addition to their 

 large factory at Torreon, acquired 

 possession of the old Hacienda de Cedros 

 in the northern part of the State of 

 Zacatecas, consisting of 2,500,000 acres, 

 valued especially for the growth of 

 guayule which it supports. The Madero 

 brothers of Barras are said to own or 

 control 3,000,000 acres of guayule lands, 

 and there are other large interests 

 besides these, 



The rate of consumption of guayule is 

 a subject of interest and importance. 

 With several well-equipped factories in 

 active operation working, at least a part 

 of the time, both night and day, the in- 

 road upon the supply is a matter demand- 

 ing consideration. Although the acreage 

 above cited seems large, the fact is 

 that only parts, favoured situations, of 

 these large holdings actually produce 

 the plant — the foothills especially, of 

 limestone formation. A single factoi'y 

 may consume 30,000 tons of guayule 

 shrub in a year, or approximately 100 

 tons a day. This may represent the 

 growth on anywhere from 25 to 100 acres 

 of land. The number of plants on an 

 acre, and the weight of the individual 

 plant, vary so much that no constant 

 figures can be given. One may find on 

 guayule lands a standof from 1,000 to 2,000 

 plants to the acre, and the plants weigh 

 any where up to 15 pounds (very large); 

 probably the majority of the plants 



