112 



is immaterial, as far as the keeping quantities of the rubber 

 are concerned, whether the entire moisture or only part of 

 it is removed, as the moisture enclosed in the rubber is 

 free from live putrefactive germs and can do no harm. 



Rubber prepared by this method both in the Amazon 

 District and in Ceylon has proved to be equal to the best 

 para sorts. Goods made from Purub prepared rubber 

 appear to have superior keeping properties. There was no 

 difference at the time of manufacture between goods made 

 from Ceylon rubber prepared in the usual way with acetic 

 acid and goods made from Ceylon rubber prepared by the 

 fluorine treatment, but after H years the material prepared 

 with fluorine showed much more elasticity than the other. 

 Dr. Frank and Dr. Marckwald have examined this charac- 

 teristic and believe the difference arises in the vulcanisa- 

 tion. Purub rubber, they say, may be vulcanised extremely 

 quickly. Added lead oxide was not sulphurised. In fact 

 the rubber takes up the sulphur more quickly than a chemi- 

 cal combination between lead-oxide and the sulphur can be 

 completed. It may be taken as fairly certain that rubber 

 coagulated by Purub exhibits particularly good properties 

 in manufacture. 



There has been references to Purub in recent numbers 

 of the "India Rubber Journal" arising out of a summary 

 of a lecture on the material by Dr. Frank at the Rubber 

 Exhibition. From these we gather that it would be wise 

 for any Planter who gives Purub a trial to indicate clearly 

 on his rubber that Purub has been used as a coagulator. 

 ( )ne writer records a case where a parcel of rubber gave 

 trouble because it vulcanised too quickly. A manufacturer 

 who buys a sample of Purub-cured rubber under the im- 

 pression that it has been cured in the acetic acid may suffer 

 confusion and loss. Besides indicating that Purub has 

 been used it will give manufacturers an opportunity of 

 estimating its value. M. Victor Herin has shown that even 

 "slight differences in the method of coagulation affect not 

 only the strength and elasticity of the raw rubber but also 

 such properties as its solubility in benzole." 



If all the advantages claimed for Purub are true it is 

 certainly a superior coagulator. It is at any rate well 

 worthy of a trial. 



W. J. Gallagher. 



