14 BULLETIN 1056, U. S. DEPARTMENT OF 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 EECLEANING 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, 



