324 



To obtain the output of commercial washed rubber, the crude- 

 rubber is first weighed and then washed in a flow of pure water as it 

 passes between a series of rollers moving at different rates of speed. 

 The result is '* washed rubber " and the difference in weight between 

 it and the crude rubber represents the loss in washing. 



M, Vernet proceeds then to give the loss by washing of the 

 various forms of cultivated and wild rubbers. 



Cultivated Para, No. i Crepe, biscuit, sheet or block, as made in 

 the factory. This varies, pale crepe giving a loss by washing of ^ to 

 l^A pel* cent, while biscuits give a loss of 3 to 4 per cent. 



No. 2, Clot or as he calls it Lump — the rubber which has 

 coagulated in the cups — which is always he says, more or less stained 

 with organic debris (it should not be) gives a loss of 5 to 30 per cent, 

 but when made up as crepe, only 2 to 3 per cent. 



No. 3 Scrap gives 6 to 15 per cent.. Scrap-crepe 4 per cent., 



No. 4 Bark-scrap in the form of crepe, 4 to 8 per cent. Wild 

 Para loss on washing given by Dr. W. Esch in Fabrication de Caout- 

 chouc. 





Maximum. 



Average. 



Minimum. 



Para Bolivia and Peru 



16 



14 



12 



„ Amazon Hard Cure 



17 



15 



13 



„ Island Soft Cure 



20 



18 



15 



Nanaos No. I 



28 



26 



23 



Entrefin 



25 



22 



18 



Sernamby: Niggerhead 



40 



30 



26 



(Here we see that with the exception of Clot, giving a loss of 

 30 per cent., even the scrap is cleaner than the best wild Para. Clot 

 giving anything like this loss must be very unusual and is a disgrace 

 to any estate.) 



I have shown elsewhere sufficiently clearly, he says, that in 

 Hevea Braziliensis caoutchouc and the substances which combine to 

 form it play a direct alimentary part, so that every system of too 

 strong or unsufflcient milking only induces a loss of Caoutchouc. If 

 the tapping has a direct action on the amount obtained, can it not 

 equally affect the quality of the rubber.? We do not know in what 

 form the rubber occurs in the laticiferous vessel, but we know it is not 

 in the same state as it is in the latex when it exudes from the cut. 



If we heat Hevea latex in some vessel, we obtain a clot. If we 

 heat a living branch of a tree, we, can see that when afterwards we 

 break the bast bark the laticiferous tubes do not contain threads 

 of rubber, though this occurs under the same circumstances in the 

 stalks of rubber producing Apocynaceae. The different substances 

 which combine in the formation of Caoutchouc in the latex of Hevea 

 cannot be produced with equal rapidity, it follows then that the 

 methods of tapping of different intensities may exercise direct and 

 variable influences on the value of the Caoutchouc. 



