Gums, Resins, 



458 



[Nov. 1900. 



(the European Agents of one of the largest Guayule rubber producing firms in 

 Mexico, the Companhia Explotadora Coahuilense, Parras) to come over to 

 England and demonstrate to the manufacturers here that Guayule rubber possesses 

 qualities which fit it for the manufacture of many grades of rubber goods, and these 

 not at all inferior ones. While the opinions of Dr. Eseh in this connection might 

 not be taken as unprejudiced, since his mission was to prove the case for Guayule, 

 yet it is only fair to state that for a long time back, without any material consi- 

 deration which would affect his judgment one way or another, Dr. Esch has been 

 active in his advocacy of Guayule, as his articles in the technical press can 

 demonstrate. 



In our interview with Dr. Esch, he pointed out that it was a 

 curious fact that Guayule, the cheapest of all genuine raw rubbers, was 

 until recently unknown to many English rubber manufacturers. Some had been 

 reading about this rubber; some had seen samples of it, but altogether there 

 were only two manufacturers who knew how to make profitable use of this cheap 

 raw material. 



The reason why Guayule rubber was first of all introduced to Germany had 

 its origin in the fact that the Germans first discovered it, and even yet mainly 

 German-Mexican firms do the business in this rubber. From the beginning Dr. 

 Esch has been interested in Guayule, as he had the conviction that useful rubber 

 goods could be manufactured of this rubber, and he used all his influence to extend 

 a knowledge of this rubber. 



In spite of unfavourable criticism, Dr. Esch states that he stood 

 his ground, and now no expert doubts any longer that Guayule belongs to the 

 class of genuine rubbers, and hundreds of tons of it are now used in large 

 rubber works. 



Although the period of its introduction has not been very long, Dr. Esch 

 stated that there are now used hundreds of tons of Guayule rubber in the United 

 States, and that the Companhia Explotadora Coaliuilense, , in Parras, Mexico, alone 

 has, to his knowledge, sold in the last few months, say 000 tons. 



At the beginning the attempts of several manufacturers to use Guayule 

 resulted in failure, but these failures, according to Dr. Esch, are not difficult to 

 explain, and the mistakes they made can be easily avoided. Guayule is a very 

 peculiar product. It cannot be treated in the same way as Para or other kinds. 

 The small Guayule bush does not contain latex, as do other rubber trees, but 

 rubber already of a rather consistent kind ; and that is the reason why the 

 collection of this rubber is a very peculiar one. The Guayule rubber imported 

 from Mexico still contains wood fibre. If one tries to remove this fibre, as 

 in the usual way by washing machines, one never will get at the end a pure 

 rubber. Through the pressing and squashing of the washing mill this wood 

 fibre is forced into the rubber, which, by this time, is getting softer and 

 softer, and a real removal of the fibre seems impossible. If the rubber is hung up in 

 thin sheets, as the otlier kinds, to dry, it will become apparent that air does not dry 

 it. If one makes thicker sheets in order to avoid the tearing from the sticks, it will 

 not dry completely at all. 



Very often Dr. Esch has found in Guayule rubber washed and dried in this 

 way alkali residues, which still remained in the rubber, and from the alkali which is % 

 used in the usual Mexican treatment of the Guayule shrubs. In all such cases the 

 use of Guayule rubber which lias Igone through these operations has the disadvant- 

 age of making the goods porous. 



