2 BULLETIN 288, U. S. DEPAETMENT OF AGEICULTUEE. 



should prompt individuals and communities interested in keeping 



their cotton seed pure to bring about some form of cooperation 



with ginners to effectively provide against the admixture of varieties 



at the gin. 



THE POSSIBILITY OF MIXING SEED. 



The matter of preserving the purity of cotton varieties has not 

 been given attention in the designing of ginning machinery, and the 

 different machines and their accessories are installed without refer- 

 ence to the amount of seed mixing likely to occur. Since either 

 the quantity of seed cotton ginned or the output of baled lint governs 

 the profits of the ginner, he usually operates his plant from the 

 standpoint of output alone, the seed question being purely secondary 

 with him. Consequently there are several stages in the ginning 

 process where mixing occurs unless certain precautions are exercised. 



The methods generally employed in the operation of custom gins 

 are about as follows: 



A patron's seed cotton is taken up from his wagon by suction and is conveyed by 

 the same force through flues to the battery of gins. The manner in which the seed 

 cotton is distributed to the different gins, usually two to four in number, and the 

 condition in which it enters them vary somewhat with the type of ginning outfit 

 used. Usually, however, the distribution is preceded by a certain amount of mechani- 

 cal beating and pulling, the purpose of which is to clean the seed cotton as much as 

 possible and properly condition it for the actual ginning operation. 



The seed cotton enters each gin through a kind of box called the feed box, or feeder. 

 The space between the feeder and the saws, where the actual separation of lint and 

 seeds takes place, is inclosed by a concave metal surface, and this inclosure is called 

 the roll box. 



Upon entering the roll box the seed cotton falls upon the ribs of the gin breast. 

 Here the saws, one of which protrudes between each pair of ribs, catch the lint in their 

 rapid, revolving motion, pull it from the seeds, and carry it on their teeth to the 

 brushes, which in turn take it off the saws and pass it into the lint flues, through which 

 it is conveyed by suction to the press. The seeds, being imable to pass between the 

 ribs with the lint, fall back and are diverted by means of an inclosed metal apron into 

 the seed conveyor. This conveyor, which usually consists of a screw or a belt in a 

 groove or trough arranged directly under the gins, takes the seed either to hoppers, 

 from which it may be dumped into the patron's wagon, or to the seed house, from which 

 it will later be shipped to the oil mill. 



As the saws tear through the seed cotton first fed into the roll box they give to the 

 mass a rotary motion. This revolving mass soon assumes the shape of a roll, which 

 gives rise to the ivto "roll box. " 



Gradually most of the lint in the roll is removed, and it becomes more truly a roll of 

 seed. The regulated supply of seed cotton subsequently fed int <> i he roll box revolves 

 upon the roll, the lint is caught by the saws and carried away, and the seeds remain 

 as part of the roll or drop, out into the conveyor. Thus, there is a constant exchange of 

 seed in the roll. 



Once formed, the roll is seldom removed, but usually is allowed to remain through 

 1< >i i-_r J m rimls of g inning . The ginner ordinarily' tries to avoid having the roll run out or 

 dropped, which would neeessi'ate the formal ion of a new one when i he next lot of cot- 

 ton is fed to the gin. Sometimes the gins are stopped jusl before the last seed cotton 

 of a patron passes out of the feeders, and the amount remaining is ginned as the first 

 part of the next patron's cotton. Usually, however, the gin is run several minutes 



