December, 1908.] 



513 



Saps and Exudations. 



long, doubled up several times, and 

 macerated, to draw out the juice; the 

 stems were then removed, squeezed 

 out, and the remaining liquid strained. 

 It was then thoroughly incorporated in 

 the latex by stirring with the same. 

 Although many claims have been 

 advanced in favour of the employment 

 of certain chemical reagents to assist 

 the process of coagulation, the superi- 

 ority of such over the simple means 

 above described has yet to be proved. 

 In the course of an hour or two the 

 caoutchouc globules would be found to 

 have coalesced in the shape of a spongy 

 mass, easily lifted out of the residual 

 liquor. This mass was laid on a table 

 and cut up into convenient strips, of 

 about J£ in. in thickness, which were 

 immediately passed a number of times 

 through the hard-rubber rollers of an 

 ordinary wringing machine, the rollers 

 being gradually adjusted until the strips 

 had been reduced to about \ in. in 

 thickness, and containing the minimum 

 (or, rather, the advisable minimum) 

 of moisture , for as with Hevea, if too 

 much moisture be taken out of the rub- 

 ber, it results in a loss of elasticity and 

 strength, the product becoming soft and 

 gummy, if stored for any length of 

 time, or subjected to pressure or a raised 

 temperature ; while, on the other hand, 

 the retention of a large proportion of 

 moisture is liable to set up putrefactive 

 changes through the development of 

 bacteria. The strips were next immers- 

 ed for a few moments in clean water, 

 to remove any traces of the extraneous 

 black liquor ; then taken out and hung 

 up to dry on bamboo rods suitably 

 arranged under the corrugated iron 

 roofing of the drying shed. At the 

 expiration of a month the rubber was 

 ready tor packing in bales for shipment. 

 When the strips were freshly washed, 

 ready for drying, they were about the 

 colour of dough or very light putty ; 

 after a few days, however, they assumed 

 a pale brown superficially, but retained 

 the original dough colour internally for 

 an indefinite period. 



Castilloa rubber prepared in this 

 manner has been found to rank very 

 high in quality for manufacturing pur- 

 poses. Attempts have been made to 

 produce what was thought would be 

 a still higher grade by repeated wash- 

 ing of the latex until the residual liquor 

 came off almost colourless, the latex 

 being then transferred to shallow, 

 porous earthenware pans, and allowed 

 to stand until atmospheric coagulation 

 took place, requiring from five to ten 

 days before the biscuit thus formed 

 could be removed, The resultant pro- 

 duct presented at the time, in all 

 65 



apparent respects, the most attractive 

 example of castilloa rubber. Later ex- 

 perience, however, has conclusively 

 demonstrated the fact that rubber so 

 treated becomes "tacky" and deteri- 

 orates much quicker than that obtained 

 by the usual method ; nor, indeed, does 

 such rubber, upon removal from the 

 coagulating pans exhibit nearly the 

 same strength of fibre resilience. Just 

 what the precise physical or chemical 

 causes may be that contribute to these 

 results must be left, of course, to labor- 

 atory investigation to determine. 



It has been observed that in compara- 

 tively young trees, such as those referred 

 to, the flow of fluid latex was less than in 

 older trees ; that is to say, that immedi- 

 ately upon tapping, while a small pro- 

 portion ran freely, atmospheric coagu- 

 lation began very soon, the result being 

 the formation of a creamy latex in the 

 incisions, too thick to run, which in a 

 few days could readily be stripped from 

 the trees as "scrap" rubber, or " grena," 

 as it is locally termed.— Tropical Life, 

 Vol. IV., No. 8. August, 1908, 



A NOISELESS LONDON. 



What Rubber-Paved Streets 

 Would Accomplish. 

 (D. Mail.) 



When Sir Henry A. Blake declared 

 open the International Rubber Exhibi- 

 tion at Olympia on Monday, he had 

 around him in the great building — ac- 

 cording to an expert computation — near- 

 ly £1,000,000 worth of pure rubber. 



"Rubber," declared Sir Henry, "is a 

 product that has during the past half- 

 century played a greater part than any 

 other substance in expediting human 

 progress " As proof of this statement, 

 he added : "Without rubber no cables 

 could have been laid down between far- 

 distant continents to give the means 

 of that instantaneous communication 

 which makes for peace, friendship, and 

 commerce." 



Ousting Leather. 

 Last year £11,000,000 worth of rubber 

 was imported into this country ; but the 

 romance of rubber lies not in figures, 

 but in the extraordinary variety of its 

 uses in modern life— as evidenced upon 

 the stalls of the Exhibition. The work- 

 ing of every factory is now depended in 

 some way or another upon rubber. 



Rubber is now doing its best to oust 

 leather for some purposes, For machine- 

 belting, for instance, it is claimed that 



