

THE 



POPULAR SCIENCE 



MONTHLY. 



OCTOBER, 1912 

 THE GUAYTJLE— A DESERT RUBBER PLANT 1 



By Professor F. E. LLOYD 



MCGILL UNIVERSITY 



T3ERHAPS no statement in regard to the source of our commercial 

 -L rubbers is more surprising to one unacquainted with this partic- 

 ular field than that over 200 species of plants contribute to the sum 

 total of the crude material which comes to the market. Indeed, that 

 " rubber plant/' which is frequently used as a household decoration is 

 usually thought to be chiefly responsible, but this is far from the truth. 

 This same rubber plant, however, furnishes us with a point of departure 

 for the present account in the fact, well known to every one who has 

 but slight acquaintance with it, that when injured, a milky fluid (latex) 

 escapes, which, on drying, becomes translucent, and displays in some 

 degree the familiar properties of india-rubber, or caoutchouc. 



Diverse as are the plants which furnish caoutchouc, until a few 

 3^ears ago practically all of it was obtained by " tapping." This con- 

 sists in cutting into the bark of the plant, and collecting either the milk 

 (latex), to be coagulated immediately or later by various methods, or 

 the strings and masses of coagulated latex adhering to the wound or 

 elsewhere. Among the latex plants the only exception worthy of men- 

 tion is the so-called grass or root rubber of the Congo. The rhizomes 

 of the various species, which, because of their position, can not be 

 tapped, are collected and dried, whereby the rubber is coagulated in the 

 latex-tubes. It is subsequently extracted mechanically by heating, 

 under such conditions as to separate the rubber from the fiber. It will 

 appear evident that whenever the rubber exists as such within the plant, 

 either as the result of coagulation or for any other reason, other meth- 

 ods than that of tapping must be resorted to for its extraction. The 

 practise in the case of the root-rubbers suggest comminution of the 



1 For a full account see F. E. Lloyd, ' ' Guayule, a Rubber Plant of the 

 Orihuahuan Desert," Carnegie Institution of Washington, Publication 139. 



vol. lxxxi. -22. 



