13 



Saps and Exudations. 



curiosity of our readers in giving them an opportunity of perusing in English 

 one of the most amazing documents it has been our fortune to read. The writer 

 apparently has never heard of Hancock's investigation in this direction. 



The following article does not treat of any artificial or so-called regen- 

 erated rubber, but refers to natural rubber of first-class quality, in a word, of Para, 

 but a quality of Para purer than that gathered in the plantations of Ceylon, 

 although this is reputed to contain but 1-h per cent, of impurities. 



The new idea, the revolution, resides solely in the method in which this 

 product is prepared ; in effect it aims at the almost total suppression of the 

 costly plant that the manufacturing of rubber requires, by reducing it to its 

 most simple expression — and it proposes to do this by starting from an entirely 

 new base, that of the latex itself, in place of its dried extract, alone employed 

 for industrial purposes to-day .... The property of a substance, so rebellious to 

 all coercion as gomma elastica or rubber, is precisely to return immediately and 

 incessantly to its primitive form, as soon as an outside power, which has been 

 forcing it into another direction, ceases its action. This is the essential property 

 of rubber, the reason of its existence one might say, and the essence of its 

 being— but this property has its defective side— its irreducibility to all con- 

 formation .... 



Let us go into a rubber works and watch this incredible transformation, 

 this marvellous exhibition of skill which takes place every day. Take the purest 

 of the so-called gums, the cleanest, that which is prepared Avith infinite care 

 by the Indians of the Amazon and Orinoco basins— the Para. This sort still con- 

 tains about 10 per cent, of impurities, notwithstanding the precautions taken 

 by the natives, who have, however, necessarily neglected the only reliable one 

 now employed in Ceylon, the filtering of the latex, or milk of the Hevea, which 

 yields the Para. The blocks of Para are sliced up and passed through a washing 

 mill, consisting of two strong horizontal rollers of eqtial diameter, driven by 

 steam and turning towards each other. The same material may be passed 

 through the rollers twenty, thirty, or forty times, while a plentiful and continual 

 watering washes away the bits of bark, leaves, and dust and other impurities 

 mixed up with the raw rubber. At length in this way a pure rough clean 

 substance is obtained, in form of sheets which are left to dry in free air, during 

 weeks at a time, when the excess of water should be naturally evaporated. 

 Then the sheets are passed on to a mixing machine, where are incorporated 

 other inferior rubbers of different kinds, and to this mass is slowly and gradually 

 added a crowd of ingredients, of which the principal purpose— though generally 

 denied— is to substitute heavy and cheap substances for Para rubber, which 

 at present costs 5s. (id. per pound. Thus are added sulphate of lime, oxide of 

 zinc, litharge, wood-powder (lycopodium), and sulphur, which will presently serve 

 for the vulcanization. Of this last product rubber can be made to absorb up 

 to 10 per cent, and even 25 per cent, for vulcanite, and an up-to-date mixing 

 machine may cost £1,600 ! The cyclopean rollers powerfully and remorselessly mix 

 and knead the resisting crackling mass, and the mixing is carried on for long hours, 

 until at last the compound is thoroughly coherent. It is sufficient to have once 

 assisted at this extraordinary triumph of mind over matter, to notice how 

 tenacious the elastic properties of rubber must be, to be preserved throughout 

 this remarkable treatment. To say that the properties of rubber do not suffer 

 would be nonsense, but at last a sheet of equal thickness has been obtained, 

 from which different parts of the object to be manufactured may be cut out 

 by punches or other methods .... 



