464 



work'; and to this end I have had made in Manchester, by a firm 

 of manufacturers of rubber machinery, at the expense of the 

 Colonial Government, machines for practically working up and 

 vulcanising rubber, and I intend with the aid of these machines 

 to manufacture test pieces of vulcanised rubber from raw rubber 

 taken from trees grown in various localities of different age and 

 cured in different ways. With these samples of vulcanised rubber 

 physical tests of elasticity and tensile strength will be carried out, 

 and a just comparison of the samples among themselves, and with 

 true South American Para, can be made. There are special diffi- 

 culties in carrying out physical tests on india-rubber, and there is 

 at present no uniform method of stating results ; comparisons 

 between tests made bv different places are therefore of little value, 

 and it is essential that all the work be done in the same manner on 

 the same type of apparatus, to eliminate the personal equation and 

 correctly ascribe to each variant factor in the production of the 

 raw rubber its consequent variation in the quality of the product. 

 When this is done I shall be able to say with certainty which 

 method of preparation gives the best results, and to ascribe cor- 

 rectly to each and every one of the variable conditions under which 

 the rubber is produced its true influence on the quality of the 

 rubber. This work I look upon as being important, and it will, 

 I trust, settle decisively many of the problems which now are con- 

 troversial. To see clearly the necessity for the work, and to have 

 gained the insight into the methods of treating and vulcanising 

 rubber necessary for carrying it out, are the direct results of my 

 visit to England, and the time spent in the works of the rubber 

 manufacturers there. 



PREPARATION OF RAW RUBBER. 



14. I have already stated I am not at present in a position to 

 say decisively how the rubber should best be coagulated and pre- 

 pared for export, but I am inclined to recommend that as little as 

 possible in the way of acids or drugs should be added to the milk 

 or latex. W T here a washing machine is used, the milk might, 

 I think, with advantage be allowed to coagulate by simply standing 

 for 24 or 36 hours and allowing the natural fermentation, or 

 scouring, which takes place, to produce coagulation. This of course 

 will preclude any possible additions of preservative, such as 

 formalin or dilute ammonia, to the latex in the cups and it will be 

 desirable to keep the latex as concentrated as possible. This 

 natural method is of course only possible where a washing machine 

 is used, and.it involves more time being taken in the actual coagu- 

 lation process. There is among the manufacturers an objection to 

 the use of any acid or addition of any drug at all to the rubber 

 during coagulation, from fear that traces of it might be left in the 

 rubber, even after washing. If there were an appreciable amount 

 remaining, it is highly probable that it would give trouble during 

 working and vulcanisation of the rubber by acting chemically on 

 some of the ingredients with which the rubber is mixed and perhaps 

 producing gases which would form blow holes in the finished goods. 



