Dec. 1906.] 459 Saps and'Exudations. 



It has been Dr. Esch's endeavour to show the manufacturer who*'did not 

 know how to use this rubber how to treat the raw material in order to remove all 

 impurities, and, on the other hand, how to use it in the manufacture of useful rubber 

 goods. In this method the old wash-hollanders can be used, as they cut the Guayule 

 in sufficiently small pieces without the rubber undergoing such a deterioration as in 

 the washing mills. By heating the water in the wash-hollanders the Guayule 

 expands, the particles lose their adherence, and in this way the wood fibres are freed 

 and drop to the bottom. In just the same w ay all other impurities are removed by the 

 hot water, which cold water would not do so easily. Those who do not possess a 

 washing hollander will require to cut the rubber into small pieces in another way. 

 It can be done, for instance, by cutting the wet Guayule with a machine the same as 

 is used in mincing meat, and then throwing it into hot water. 



After this treatment the Guayule, now in small pieces, requires to be washed 

 in cold water and then spread out on a wire netting and dried in dark j ooms at a 

 temperature of 30 to 40 degrees. 



Dr. Esch is confident of the fact that the product so obtained is good 

 enough even for making ebonite combs. He went on to say that there had been some 

 mixtures put at his disposal which showed (according to the opinion of experienced 

 working managers) that a vulcanite comb mixture, consisting of 2—3 Guayule and 

 1—3 Para, was apparently, at least, just as good as an analogous mixture of 2— 3 Para 

 and 1—3 Guayule. When he showed these samples in England to some experts, the 

 first-mentioned mixture was always recognised as the best one, especially on account 

 of the beautiful dark gloss. It is obvious that the Guayule, by virtue of its physical 

 qualities, is exceedingly fit for use in the manufacture of many classes of rubber 

 goods. 



Dr. Esch stated that he knew of three rubber shoe works which use plenty 

 of Guayule rubber, with very satisfactory results. Combined with mixtures, which 

 are dry through containing plenty of rubber waste, etc., Guayule makes a good com- 

 pound. One thing, however, has to be carefully considered in connection with com- 

 pounds containing Guayule rubber, namely, the slow vulcanising and the resin 

 contents of the Guayule. These two facts cause the inertia of the Guayule in the 

 vulcanisation. Guayule belongs to the class of very slowly vulcanising rubbers, and 

 these classes of rubber (as well as the ones vulcanised by steam) require an addition 

 of heavy calcined magnesia. 



Regarding the extended use of the ingredient, Europe is away ahead of 

 Britain in this matter. 



Although the magnesia added to these mixtures seldom surpasses 5 per cent., 

 the leading Continental rubber and cable works use tons of the heavy magnesia. In 

 order to avoid misunderstandings, Dr. Esch states that the mentioned limit of 5 per 

 cent, heavy magnesia is available only for the soft rubber goods, and as to certain 

 ebonite goods, for instance, packing sheets, etc., higher additions of magnesia are 

 required. 



Dr. Esch explained that as regards any further information that might be 

 desired with regard to Guayule, he would be happy to furnish it to any reader of the 

 Journal. He also stated that samples of Guayule, of any size, could be had from the 

 firm already named in this article. In these days of fluctuating prices it is not 

 always advisable to give price, but in order that comparisons may be made by any 

 • readers unacquainted with the price of Guayide, it might be stated that in small 

 quantities it cost about Is. 9|d. per lb. f.o-b. Hamburg, and in large quantities 

 Is. 6d. per lb. f .o.b. United Kingdom. The losses in washing can generally be. 

 taken in at about 25 per cent.— The India-Rubber Journal. 



