April 1, 1919.] 



THE INDIA RUBBER WORLD 



349 



Chrysothamnus or Sierra Rubber. 



WHETHER the United States in the near future is destined 

 to produce its own rubber within its limits in commercial 

 quantities is a problem which still remains to be solved. 

 The investigation which was undertaken by experts of the Uni- 

 versity of California, shortly after the United States entered 

 the war, and an account of which was printed in The India 

 Rubber World June 1, 1918, is still proceeding, but up to date 

 the investigators are of the opinion that it is not possible to 

 obtain rubber commercially from the wild plants which grow 

 so abundantly in the Sierras and in oilier parts of the West. 



Professor H. M. Hall of the 

 University of California, who 

 is in charge of the research 

 work, while declining to go 

 into detail as to the extent of 

 the discoveries until a complete 

 report can be made, is au- 

 thority for the broad statement 

 that the total amount of wild 

 shrub with a rubber content is 

 "so great that it is safe to say 

 there is enough rubber present 

 to constitute an emergency sup- 

 ply in case we ever get into a 

 war in which our importation 

 would be curtailed, but the ex- 

 traction of this would be an 

 expensive processr since the 

 average content for the whole 

 West is probably not more 

 than 2K' P^r cent, and even in 

 the best districts it will not 

 run more than 4 or 5 per cent 

 on the average." 



Professor Hall is quite cer- 

 tain that rubber cannot be ob- 

 tained commercially frotu the 

 wild plants with the price of 

 rubber anywhere near what it 

 now is. In connection with 

 this matter he says : "It is 

 sometimes stated that the 

 plants can be profitably grown. 

 This is entirely within the 

 realm of possibility, and one 

 phase of our work is looking 



toward investigation in that connection, for it would be im- 

 possible to demonstrate at the present time that there would be 

 any profit in growing the plants." 



Professor Hall's forthcoming report will contain a compre- 

 hensive resume of the possibilities of the various wild plants 

 of the western regions which are known to contain rubber. 

 There are several of them in unlimited quantities, but the most 

 "interesting sort" as Professor Hall terms it, has been de- 

 nominated the "Common Green." "This is a variety of the 

 Chrysothamnus nauseosus." he continues, "but I cannot give 

 the Latin equivalent for the varietal name at present, since the 

 variety has not been described and it would not be well to use 

 the name ahead of the description. . . . We are finding 

 that this 'common green,' as we call it, averages only about 3 

 per cent, altliough individual plants, and some of them very 

 large ones, carry as much as 6 per cent. These figures are for 

 absolutely pure rubber and arc based upon dry weight. There 

 are many interesting developments in connection with our 



Chrysothamnus Nauseosus or "Common Green, 



studies, but it is not permitted me to speak of these at present." 

 That the United States may be on the verge of a discovery of 

 the greatest importance to the rubber trade is entirely within 

 the range of possibility, and that a most important beginning has 

 been made is entirely apparent. The fact that the supply is 

 sufficient for an emergency, despite the cost involved in its 

 production, is alone well worth consideration, although the end 

 of the war has rendered it exceedingly improbable that such an 

 emergency will arise in the near future. Although sensational 

 reports have been printed from time to time in the daily papers 

 as to the probabilities of a com- 

 mercial supplyof rubber existing 

 in the West, Professor Hall has 

 not gone farther than in his 

 original statement on the rub- 

 ber discovery, which is to be 

 amplified in his complete report 

 to be made this spring. He 

 stated : 



"For two months the writer 

 carried on field surveys in eight 

 Western States in order to 

 make estimates of the tonnage 

 and distribution of rubber- 

 carrying shrubs and to gather 

 samples for chemical analysis. 

 The results indicate that the 

 total amount of rubber present 

 is much greater than we 

 originally supposed, although 

 the percentage content of the 

 shrubs is perhaps less over 

 much of the area covered. 



"Four of our experimental 

 plots in Eastern California 

 have been studied and evidence 

 obtained which indicates that 

 it will be necessary to destroy 

 the plants in order to harvest 

 the rubber. On the other hand, 

 a method is being developed 

 which gives promise of increas- 

 ing the weight of the rubber- 

 carrying portions and will be par- 

 ticularly applicable if the plants 

 are brought under cultivation. 

 "In order to get an expert opinion on the quality of 

 the product 25 pounds of shrub were sent to Dr. D. 

 Spence, chairman of the sub-committee on rubber and 

 allied substances of the National Research Council. 

 After some months, during which time deterioration probably 

 took place, the rubber was separated by the ordinary mechanical 

 lueans and a per cent of pure rubber obtained. This was tested 

 and reported upon as of 'high grade and average quality — not 

 as good as fine Para, but a great deal better than most African 

 low grade rubbers.' Dr. Spence also reported that 'the rubber 

 vulcanizes readily and gives a product of very fine quality.'" 



In order to give an idea of the inexhaustible supply of rubber- 

 producing plants in California it may be stated that there are 

 70 species of them in that state, containing from 1 to 10 per cent 

 rubber, according to Professor Marcus E. Jones, who has been 

 assisting Professor Hall. Professor Jones, who was formerly 

 with Colorado College, has extended investigations over Utah, 

 Idaho, Nevada, Wyoming, and Colorado. 



