16 

 On the second occasion the results were very similar : 



From these figures it is clear that for practical purposes the 

 effect on the worms in mabruma cotton may be regarded as the same 

 as that on the worms in sifted seed. 







The second objection to putting the heating machine between 

 the gins and the sifters is a more serious one, as may be seen from 

 Table I, from which it is clear that if the seed is rapidly cooled after 

 leaving the machine a much higher temperature is necessary to ensure 

 the killing of all the worms. The difficulty can be overcome, however, 

 by running the treated seed into an insulated vat with a capacity 

 equal to, at the very least, five minutes' output of seed. When once 

 this is full, the seed should be withdrawn from the bottom at the same 

 rate as it enters at the top. In this way every seed will remain at the 

 requisite temperature in this vat for at least five minutes before being 

 cooled down. If some such device is not employed and it is still decided 

 to treat the seed before sifting it, the temperature employed will have 

 to be higher, the exact degree depending on the rate at which the 

 seed is cooled after leaving the machine in each individual case. 



The question of controlling the temperature deserves a few 

 general remarks. In those machines in which the seed is heated by 

 steam-jackets or steam-tubes, either by direct contact or by radiation, 

 the temperature of the treated seed depends on : 



(a) The initial temperature of the seed. 



(6) The rate at which the seed enters the machine. This is 

 presumed to be, in the course of normal running, the same as the 

 rate at which it leaves the machine. 



(c) The pressure of the steam. 



(d) The time which the seed takes to pass through the machine. 



(e) The quality of the seed being treated. 



