Nov. 1900.] 



365 



Saps and fi.vudations. 



physical properties, and yet, as we know, the duplicates of the rubbers to which 

 I refer have been shown by Mr. Bamber to have approximately the same chemical 

 composition. The results of Para practically contradict the statements of Professor 

 Dunstan, and I shoidd very much like to know whether it is intended to apply 

 only to rubber of different species, or rubbers from trees of different ages with 

 which we have no acquaintance. It certainly does not apply to our own Para 

 rnbber. There was one point I omitted to mention, and that is with reference to 

 the mixing of the latex. Personally, I think it might be as well if we turned 

 out, as Mr. Ryan says, a uniform sample year by year from different estates, 

 because we are now simply starting from the very bottom. The trees can never 

 be yonnger. The age will increase year by year, and with it the quality of the 

 uniform sample, and this will be appreciated in London. 



Mr. Bamber— replying to Mr. Wright— said : With regard to the comparison 

 of Para rubber from the analysis of strength, the reason they had not been able to 

 do that at present was that they could not have a correct solvent that would extract 

 the solvent matter from the true caoutchouc. They used acids which after some 

 hours would remove the whole of what they called resin, but in the residue that was 

 left there was, no doubt, some other compound which was not true caoutchouc ; at 

 least, it had not the elastic properties of caoutchouc. They would imagine that if 

 they took good rubber and bad rubber and extracted the weaker matter, they should 

 find that both samples were the same strength ; but he found the residue of strong 

 rubber is much stronger than that of the weaker rubber. In regard to the mixing of 

 latices he could not quite agree with Mr. Ryan. He knew that a very small amount 

 of weak latex would injure or was very liable to injure a large amount of older latex. 

 They had several estates with trees of several years old. As they went on in some 

 years they got in a lot of younger rubber. If that latex was mixed with that of the 

 younger rubber, they spoiled a good sample they had turned out, and, perhaps, that 

 might injure their name. He was only referring to later on when they had their 

 rubber in bearing. He did not think it would be necessary to separate the latices, as 

 he thought after eight years there would be a fair uniformity and strengch, although 

 that ought to be a gradual matter as the trees grew older ; but he did not think it 

 was worth while taking the precaution while the rubber was in the form of latex to 

 keep the latices separate. It might mean a little trouble to the planters, but it was 

 only a few tappings from the trees as they come in year by year. That would be 

 new rubber, and it would be necessary to keep it separate for, perhaps, two or three 

 months until the trees have got thoroughly into the tapping. 



A PHYSICAL TEST. 



Mr. Wright :— Following up this point, I should rather like to ask Mr, 

 Bamber whether he thinks that in the case of other rubbers any physical test is 

 likely to be devised which will indicate the chemical composition of the raw material. 

 If Professor Dunstan's statement is correct— that the physical properties can be 

 correlated with the chemical composition, there is some ground for anticipating that 

 it may be possible by a physical test to get some indication as to the quantity of 

 resin or other ingredient in rubber, I should like to ask Mr. Bamber whether it is 

 practicable. Is it scientific ? 



Mr. Bamber :— I do not think any physical test woidd give you the amount 

 of resin. We must find something that will remove the weaker compounds of the 

 rubber. There are other physical tests now employed to determine the resiliency, 

 but it absolutely cannot give you any idea of the chemical properties. For instance, 

 castilloa rubber has a very large percentage of resin. I do not think from 

 the results of the needle test that is usually employed you can draw any deduc- 

 tion as to the amount of resin. It is possible some test may be devised that will give 



48 



