October 



SCIENTIFIC AGRICULTURE 



53 



Drying. 



As the cleaned seed is delivered with 

 the liquid, a rapid and harmless drying 

 process is necessary. For this purpose 

 centrifugal action is again employed. The 

 liquid is thro"\\m out of the seed very 

 thoroughly by a high speed extractor and 

 re-usied for separating purposes. While 

 still revolving in the extractor the seed is 

 sprayed veith clear water to remove all 

 traces of the liquid. When the seed is 

 sufficiently washed the water is turned 

 off and forced out by centrifugal action. 

 This leaves the seed free from all loose 

 moisture and in condition to dry very 

 quickly in an air dryer which re- 

 quires comparatively little heat. By these 

 means the drying is effected very quickly 

 and Avith no possibility' of damage to 

 color or vitality. The seed is immersed 

 in the liquid during the separation pro- 

 cess not more than thirty seconds. Within 

 about three minutes from the time the 

 s^ed is first wet all the loose moisture is 

 thrown out by the extractor and within 

 from thirty to forty-five minutes it is 

 thoroughly dry. 



Separations With Clover Seed. 



The results from cleaning seeds commer- 

 cially and from experimental work with 

 .small samples prove that by this pro- 

 cess many verj- valuable separations 

 can be made completely and with practic- 

 ally no loss of clover seed, which with 

 the best available sci^een and air current 

 mills can be made only very imperfectly, 

 if at all, and with a heavy loss of good 

 seed. 



It has been found that with most of the 

 botanical families the specific gravity of 

 the seeds is a fairly constant character 

 and that approximately similar results 

 are secured with seed of diffenent species 

 within the same family. The specific 

 gravity of the seeds of several of the plant 

 families is less than that of clover seeds 

 and a perfect separation is effected by 

 this process. Among these are the follow- 

 ing, containing important weeds : Sun- 

 flower family (Compositae) including 

 Ragweed, Mayweed, Ox-eye Daisy, Can- 

 ada Thistle, other thistles and Chicory ; 

 Mustard family {Cruciferne) including 



Wild Mustard or Charlock and other mus- 

 tard species, Stinkweed or Pennycress, 

 False Flax, Peppergiass and Shepherd's 

 Purse; Parsley family {Unihelliferae) in- 

 cluding Wild Carrot; Borage family {Bo- 

 raginaceae) including Blue Bur or Stick- 

 seed and Blue Weed. 



With the Grass family {Gramineae) the 

 seeds are perfectly separated from clover 

 seed if the hulls or glumes are attached. 

 When the kernel or caryopsis is hulled 

 the specific gravity is about the same as 

 that of clover seed and the separation is 

 imperfect. Unhulled timothy and other 

 cultivated grass seeds are separated com- 

 plietely from clover seed. Green Foxtail is 

 very greatlj' reduced but not always en- 

 tirely eliminated. 



Witli the Buckwheat family {Polygo- 

 naceae) the separations possible are de- 

 pendent upon the condition of the seeds. 

 The specific gravity of the true seed is 

 about the same as that of clover seed but 

 most of the species normally have an outer 

 seed coat of lighter material which makes 

 separation possible. This is usually true 

 of Sheep Sorrel and to a lesser extent of 

 Docks. 



The Plantain family {Plnntaginaceae) 

 seeds are mostly of a slightly less specific 

 gravity than clover seed but the differ- 

 ence is not sufficient to make a perfect 

 separation. Buckhorn or Ribgrass is usu- 

 ally reduced about 75 per cent while with 

 Common Plaintain and other species the 

 separation is somiewhat better. 



The seeds of the Pink family (Caryophyl- 

 laceae), including Cockles, Night-flower- 

 ing Catchfly and Bladder Campion are of 

 nearly the same specific gravity as clover 

 seed and these separations are not com- 

 plete. 



With the pea family (Leguminosae) the 

 specific gravity of the various species is 

 practicall}' the same and it is impossible 

 to make a separation of Black Medick or 

 Trefoil or other wild clover .seeds from 

 those of cultivated sorts. 



Small Loss in Cleaning. 



A very great advantage of the process 

 is that the loss in cleaning is very small. 

 In attempting to remove weed seeds which 

 are nearly the same specific gravity as 

 clover seeds bv the ordinary mills a heavv 



