January i, 1910.] 



THE INDIA RUBBER WORLD 



117 



Gathering Guayule in the Texas Fields. 



or 1905, the whole industry was in an initial experimental 

 condition, and produced little more than results of prophetic 

 significance. 



So far as we may ascertain, this experimentation took two 

 trends, toward a purely mechanical method and toward a 

 chemico-mechanical method, and, if we may depend on reports, in 

 a very few instances, efforts have been made to use a practically 

 purely chemical method, consisting of solution and differential 

 precipitation. As our knowledge does not permit us at the 

 present to believe that this method can produce a rubber which 

 retains its characteristic physical qualities, we need not con- 

 sider it seriously. On the other hand, the obvious lesson de- 

 rived from the mastication of the rubber bearing tissues — the 

 first learned by every one who becomes interested in guayule 

 plant — led to the adaptation of machinery to accomplish this 

 same end on a commercial scale. The separation of the fiber, 

 or bagasse, from the rubber, was, however, more difficult, and it 

 was at this point that the aid of chemicals was sought. No 

 very apparent function was, however, at first attributed to that 

 most used, caustic soda, and the earlier patent papers reflect an 

 empirical and uncertain attitude. Avoiding insignificant detail, it 

 will serve the present purpose to indicate the essential features 

 of the process which has produced the generally best results. 



The shrub is collected in the field either by pulling it up by 

 the roots, a method causing irreparable injury to the stand, 

 or, much less frequently by cutting at the level of the ground. 

 It is then collected and carried en burro to a central camp 

 where it is baled. This point may be on the railway or a good 

 many miles away. In the latter event, it is hauled in wagons to 

 the shipping point, and despatched by freight to the factory. 

 Here it is stacked till needed. Shrinkage between field and fac- 

 tory weights are noted so as to control certain factors of more 

 or less uncertainty. After washing, the shrub is passed through 

 crushers to produce a fairly uniform coarse pulp, which is then 

 put into pebble mills. The interior structure of this machine 

 has been the subject of numerous patents. Steel balls have 

 been used, associated with corrugations or projections of vari- 

 ous kinds, but without bettering the standard mill charged with 

 Norwegian flint shore pebbles. The mill — merely a short cylinder 

 — is rotated on its axis until the rubber is agglomerated, when 

 the charge of water, rubber and bagasse is discharged and con- 

 veyed to skimming tanks where the water-logged bagasse sinks 

 and the rubber floats and so may be separated. A part of the 

 bagasse does not, however, sink, namely, that derived from the 

 cork proper of the bark and the water-logging of this is accom- 

 plished under water either by pressure or by continued soaking. 

 Beater-washers may be employed for perfecting the separation of 

 bagasse. 



The rubber as thus prepared contains about 25 per cent, of 

 resin, but this amount may be reduced by boiling in the weak 



Baling Texas Guayule with a Pre>s. 



solution of caustic soda, which appears to accomplish this, in 

 part at least, by saponification of the resin acids present. This 

 treatment produces a rubber with 1; to 18 per cent, of resin. 

 The rubber is now in a granular condition. By means of rolls 

 it is further washed and sheeted, when it is ready for packing. 

 It may be merely shipped in sacks, the rubber containing 25 per 

 cent, moisture, or it may be further dried, and pressed into 

 solid blocks of clean rubber, and in this shape, packed in boxes, 

 it presents an attractive appearance. The best results which 

 have been attained, so far as I am aware, by this or essentially 

 similar processes, is an extraction of 15 per cent, of rubber with 

 25 per cent, of moisture. 



Extfnt and Future of the Industry. 



The industry as such is now, let us say. four years old. Within 

 that time, so far as statistics are available* there has been a 

 total exportation of crude rubber from Mexico of 37.932,986 

 pounds, 80 per cent, of which came to the United States. On 

 a basis of 7 per cent, extraction of crude rubber of 25 per cent, 

 moisture, this would represent 328,292 tons of shrub. On a basis 

 of 15 per cent, extraction we should have 153,111 tons of shrub. 

 Add to these items the amount of shrub exported as such during 

 2j4 years, for wdiich period alone statistics are available, and 

 wo have the limits 331,035 and 155.853 tons. If we should as- 

 sume a 9 per cent, basis of extraction, wdiich would not be far 

 wrong in the average, we should have 191,389 tons of shrub 

 consumed till the present time (September, 1909). It is prob- 

 able that this estimate is not far wrong, and represents about 

 one-half of the total supply as originally estimated. It now 

 seems that this estimate, made by Endlich, was perhaps not 

 quite liberal enough, but it is unsafe to make any assertions. 



Here then, appears to be the situation. An industry a trifle 

 over four years old. represented, according to Mr. Henry C. 

 Pearsonf by about $30,000,000 of capital from the United States 

 alone, has, at the present rate of manufacture, a four-years' fur- 

 ther natural supply of raw material, roughly s-eaking. The 

 further concentration of manufacture in a few hands coupled 

 with a steady, controlled output, might be made to result in such 

 regulation that the supply, supplemented by the reduced amount 

 which may be expected to come on in the fields, may last a few 

 years longer. I venture to say, however, that further manu- 

 facture without due heed to rigorous forestry methods can 

 end only in the practical extermination, for an extended period, 

 of the natural stand. 



What these methods may be cannot be detailed here, beyond 

 to say that of first importance, in view of the reproductive 

 habits of the guayule already described, is the adoption of the 

 cutting method of harvesting to replace the pulling. This will 



•Summarized in The India Rubber World, September i. 1909— page 424- 

 -F. E. L. 

 IThe India Rubber World, August 1, 1909 — page 383.— r. e. l. 



