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such an extent by scientifically established methods 
of handling and treatment of the latex and sub- 
sequent treatment of the derived coagulum, that 
the advantages to the manufacturer of the vulcanized 
material are highly important. Recent publications 
on the work by Stevens, Whitby and by officers of 
the Department of Agriculture have added materially 
to the knowledge of the constituents of Hevea latex 
and the effect which those constituents have collec- 
tively and separately on the ultimate properties of 
raw rubber and its behaviour during and after 
vulcanization. 
Further, the extensive and increasing use of organic 
vulcanization accelerating agents, more especially in 
America, has given an entirely new aspect to many 
problems of the rubber industry. In any considera- 
tion of possible future changes in methods of pre- 
paration or even in improvements in details in the 
manufacture of the present types of plantation 
rubber, due regard must be paid to manufacturers’ 
requirements. In this connection it is desirable, 
therefore, to direct attention to other types of 
variability met with in the factory at the present 
time. 
Complaints have been made by manufacturers in 
respect of two other types of variability of the raw 
material. These consist of a lack of uniformity in 
the case of “breaking down” on the hot mixing 
rolls and in the properties of solutions prepared from 
the raw rubber. 
No investigations have yet been made to ascertain 
the cause of these types of variability, which are 
probably connected either with the state of poly- 
merisation of the caoutchouc in the raw rubber, or 
