MACHINERY AND MANUFACTURE 



199 



ments. On some other estates the division of grades and the 

 proportions in practice are approximately as follows: 



First -latex rubber 

 Second grade ,, 

 Third 



Fourth 

 Fifth 



(lump-rubber) 



(scrap-rubber) 

 ( (bark-shavings and | 

 ) cup-washings) \ 



(earth-rubber) 



75 per cent. 



5 

 10 



5 

 5 



100 



The objection to this is the manufacture and the keeping 



FIG. 55. A Battery of Mills, Back-shaft-driven (Shaw & Co.) 



separate and packing of so many grades, some of which must be 

 quite small lots. 



When rubber is smoked the smoking assists one in assembling 

 in fewer groups the various grades, as slight differences in 

 appearance are not so easily determined. This is a distinct 

 advantage when grading rubber for packing. 



After the thin sheets of crpe-rubber have been hung up 

 for a time, so that much of the water may drip off, they are sent 

 to the drying-house or to the hot-air driers to be dried. When 

 blanket-crepe is desired the thin sheets of dried crpe-rubber 

 have to be slightly damped and several sheets compressed 

 together by the rollers of the finishing-mill. This, of course, 

 involves a subsequent further drying of the " blankets/' as 

 they cannot be packed wet. In some cases endeavours have 

 been made to form the sheets of crpe into blanket-crepe with- 



