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 
many 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 be discharged through the gate of the machine as usual. 
