6 BULLETIN 927, U. S. DEPARTMENT OF AGRICULTURE. 



allows only the seed to fall through. A slow stream of water enters 

 the trough at the upper end and overflows at the lower end. The 

 waste is continuously introduced with the water, thoroughly agitated 

 with it, and carried slowly forward. In this movement the mass be- 

 comes disintegrated, allowing the seed to settle slowly, while the skins 

 are carried forward and discharged by the overflow or skimmed off 

 by workmen. When the seed accumulates above a certain point in 

 the trough the operation is discontinued and the trough dumped. 

 The seed is then placed in muslin bags and centrifuged for about half 

 an hour, to remove the excess moisture, and then dried. One disad- 

 vantage of this method lies in the fact that it requires the entire time 

 of several workmen. Such practice pays when the seed is intended 

 for planting purposes, in which case it brings a comparatively high 

 price, but if intended for crushing for oil it is not profitable. 



Another method which has been developed on a commercial scale 

 consists in dumping the waste into a large funnel-shaped receiver, 4 

 to 5 feet in diameter at the top and possibly as deep, filled with water 

 which has been given a circulatory- motion by impinging several 

 streams of water set at small angles to the surface. As it is dumped 

 into the vessel the waste is disintegrated by the swirling motion. The 

 seeds sink, while the skins are carried over the top in a continuous 

 overflow. When a large quantity of seed has accumulated the action 

 is stopped, the vessel tilted, and the excess water poured off. The 

 container is then restored to its original position and the seed dumped 

 by a gate valve in the bottom. It is estimated that by this method 

 about 90 per cent of the seed is recovered. Two men operate the en- 

 tire recovery equipment, including the seed separation and the dry- 

 ing units. Such a machine is large enough to handle all the waste 

 from a 5,000-basket plant. 



In Italy the waste is first dried and the seed then fanned out. The 

 advantage of this method is that the seed is rendered available by 

 one operation. The disadvantage, however, is that some of the seeds 

 are lost because, in drying, the particles of skin curl back and inclose 

 man}^ of them. It is not believed that any amount of grinding 

 and fanning can recover all or nearly all the seed, although no figures 

 are available as to the efficiency of such operations. 



The most practical method for separating the seed from the waste 

 is to make the separation in the original cy cloning operation used in 

 making the pulp, thus entailing only one handling. The operation 

 is continuous, with no intermittent discharge and with no extra labor. 

 To all who operate the ordinary cyclone pulping machines (fig. 3) it 

 is apparent that if the perforations of the screen are just large 

 enough to permit the passage of the seeds, these with the pulp will 

 flow out of the machine in a continuous stream, while the cores and 

 skins will })c discharged through the irate of the machine as usual. 



