10 



BULLETIN 927, IT. S. DEPARTMENT OF AGRICULTURE. 



to the spongy character of the seed it emerges from the machine in a 

 light, puffy condition, which obviates the necessity for grinding. 

 Expellers of this type are manufactured in three commercial sizes, 

 handling 400, 800, and 1,600 pounds of raw material an hour, with a 

 power consumption of 5, 7-J, and 10 horsepower, respectively. Many 

 of the seeds are 'bruised and torn, which would render them unsatis- 

 factory for planting purposes, but the operation is quite satisfactory 

 for reducing the moisture in seed intended for oil, because for this 

 purpose such bruising is immaterial. 



Drying is one of the most important processes in the successful 

 and economical handling of the seed. Various types of machines for 

 this operation are on the market. These may be classed under two 

 general heads, tray driers and rotary driers. 



Fig. 5. — An experimental moisture expeller : Open. 



The tray drier is most frequently employed for drying tomato 

 seed intended for planting purposes. The seed, freed from as much 

 water as can readily be drained off or as can be removed by slight 

 pressure in some form of press, is spread out on trays in layers ap- 

 proximately one-half to 1 inch in depth and subjected to a slow 

 current of warm air. In some cases no artificial heat whatever is 

 imparted to the air current, the lack of heat being made up by greatly 

 increasing the volume of air passed over the seed, which is pro- 

 tected from being blown away by placing a screen over the layers. 



It is claimed that this treatment insures a high percentage of 

 germination and is therefore perfectly feasible when the seed is 

 intended for planting purposes ; but for seed intended for oil extrac- 

 tion it is too expensive, since it involves a greater initial cost for 



