396 COTTON 



30 to 40 C. in Egypt according to the season of the 

 year. However, the main variable factors will remain 

 the temperature of the hot air used, and the time allowed 

 for action. 



A machine to apply the hot-air method of destruction 

 of Gelechia larvae would in principle consist of an endless 

 band to carry the seed, heated either by steam pipes or 

 other radiators, or else heated by a hot-air blast. Instead 

 of one, several endless bands might be required, one 

 above the other, each receiving the seed from the one 

 above it, and discharging on to the one below in order 

 to economize space. 



As already stated, the temperature required would 

 depend on various factors, amongst which the construc- 

 tion of the machine and the time allowed for the seed to 

 traverse the heated part are the most important. The 

 permissible temperature would have to be found for each 

 machine. 



A machine on the lines sketched above has been erected 

 by the State Domains Administration by way of a large 

 scale experiment, and having been found to be satis- 

 factory, a full-sized machine is now being built by that 

 Administration. 



(2) Treatment with Gases. Cotton seed can also be 

 treated successfully by carbon bisulphide and other gases. 

 Again an indispensable condition is that the seed must 

 not be treated in sacks. We find that the best results are 

 obtained by placing the seed in vats that can be sealed 

 hermetically, and by making the gas circulate through 

 the seed by means of a pump, which sucks the gas out 

 through a pipe at the top of the vat and forces it in again 

 through a pipe entering from below. Without some such 

 arrangement the gases do not seem to penetrate to any 

 depth through the seed, and consequently are not able to 

 kill the larvae. 



We are erecting a machine with which we will be able 

 to deal with 40 to 50 tons of seed daily as an experiment. 

 This machine has already been used on a few tons of seed 

 intended for exportation, and the samples examined 

 showed that the operation had been successful. 



The gas giving the best results has hitherto been 



