nium and "tatanini" (Parthenium lyratum) afford material to the hand of the ball enthusiast of northern Mexico. These two plants, however, contain rubber in very meager quantity as compared with guayule.
This method of extracting the rubber, viz., by mastication, very naturally suggested the course of manufacture. As early as 1888 it was
proposed to extract the rubber "by a process of grinding and washing." A test carried out in New York by the interested company showed that the "bark" contained at least "18 per cent, rubber comparable to the best grade of centrals." But nothing further was done and samples sent about this time from Mexico to Germany and England, found no favor.
In 1900, however, some Germans established a laboratory at San Luis Potosi, the birthplace of the industry in Mexico. Two years later, as a result of the San Luis investigations, a factory was started at Jimulco, in which a method of extraction by solvents was used. It was at this time that the experimental operations carried on by Mr. Lawrence and leading to the practical solution of the mechanical method, culminated in the first commercial shipment of crude guayule rubber, extracted by mechanical means. This was the American and, indeed, most important contribution to the solution of the problem, and led, as above stated, to the establishment of the works of the Continental-Mexican Rubber Company.
That the rationale of the mechanical operations involved may be appreciated, we may now consider in some detail the structure of the plant.