14 BULLETIN 1056, U. S. DEPARTMENT OE AGRICULTURE. 
them in some finely pulverized material sprinkled with water to 
paste down the surplus lint or fuzz so that they would separate read- 
ily. The addition of water and any foreign material, however, in- 
troduces a possibility of error in the grading because in some cases 
it changes the relative weight of the individual seeds. The mechani- 
cal process of removing the surplus lint or fuzz with delinting ma- 
chines, as already described, conditions the seed for any recleaning 
and grading operation without permitting this element of error, and 
without making it necessary to dry the seed. 
MACHINES USED. 
There are several machines in limited use for recleaning and grad- 
ing cotton seed. One type is a modified air-blast cleaner or fanning 
mill equipped with specially designed screens. A small-sized machine 
of this type, operated by either hand or power and having a capacity 
of 3 to 5 tons per 10-hour day, may be bought at from $50 to $60. 
A machine of larger capacity may be had if desired. Some of the 
earlier machines consisted principally of a revolving screen through 
which the seed passed and which was supposed to remove all dirt and 
other extraneous matter and small inferior seeds. Another more ex- 
pensive machine, combining both the revolving-screen and air-blast 
principles, is in use by a few dealers. A large capacity cleaner, al- 
ready described on page 10, is used in oil mills to remove stones, 
metallic substances, dirt, and loose lint from cotton seed before it 
enters the delinters, but this machine does not grade or separate the 
seeds in any way. All light and inferior seeds are not necessarily the 
smallest and -an air-blast separation is essential if the seeds are to be 
graded according to their specific gravity. 
DOCKAGE IN RECLEANING AND GRADING. 
The percentage of good seed lost or culled out in recleaning and 
grading is very small. The percentage of total dockage (dirt, trash, 
and light and inferior seeds) removed will vary with the cleanness 
and uniformity of the seed. Most of the dirt and trash, however, are 
removed by the gins and delinters and the dockage in recleaning and 
grading delinted seed consists principally of small and light-weight 
seed. If the cotton seed has been carefully selected and properly 
ginned and delinted, the dockage in recleaning should not exceed 5 
per cent. The dockage, however, is not a total loss, because the seed 
thus culled out may be sold for other purposes at slightly less than 
the original cost. 
Several instances are reported where dealers have discontinued 
recleaning and grading after a short time because of the seemingly 
excessive dockage and heavy loss of apparently good seed. How- 
ever, the removal of the chief hindrance to this work by delinting 
and the continued improvement in machines designed to perform it, 
