GINNING PIMA COTTON IN ARIZONA 5 
bale. In order to gin a product which will be more uniform some 
standard method needs to be recognized and applied. 
As a result of this survey it appeared that more information was 
needed regarding the principles, construction, and operation of the 
gin machinery and especially regarding the treatment which deter- 
mines the mechanical condition and appearance of the cotton in the 
bales after the actual ginning is accomplished. 
NORMAL EQUIPMENT AND OPERATION 
The following description of the various working parts of roller 
cotton gins and of their functions is given in order that a better 
understanding may be had of the necessity for changing to a more 
standardized method. The suggestions regarding the proper adjust- 
ment of the various parts were developed in conferences with com- 
mercial operators of roller gins in the Sea Island cotton district of 
the Southeastern States as well as in the Salt Kiver Valley. Though 
changes of the existing equipment may not be made at once, greater 
uniformity may be reached by gradual changes determined by a 
general understanding of the principles and requirements of normal 
gin operation, which are stated briefly in the following pages. 
PICKING AND STORING SEED COTTON 
The condition of the cotton as it comes to the gin is an important 
factor in determining the quality of the product. The farmer should 
understand the need of picking and handling the cotton so that it 
can be brought to the gin in proper condition for ginning. One dif- 
ficulty is that most farmers are without facilities for storing their 
cotton and take it to the gin as soon as it is picked, before the 
moisture content is equalized. Freshly opened bolls naturally have 
much more moisture than bolls which have been open for five or 
six days; also cotton which has been picked early in the morning 
has more moisture than cotton picked in the afternoon. If cotton 
could be stored in a dry place for three or four weeks, the dry cot- 
ton would absorb some of the moisture from the wet and a more 
uniform condition would prevail. Satisfactory ginning can not be 
done if cotton lies out in wet weather or is picked and ginned too 
soon after a rain. (PL III.) These are matters that the farmers 
themselves should realize and take the necessary steps to control. 
USE OF PICKER-ROLL CLEANERS 
On arrival at the gin the seed cotton should be examined by the 
gin manager. If the cotton has been picked clean and is in good con- 
dition for ginning it should go directly to the gins instead of pass- 
ing through the special picker-roll cleaners, as the cleaner feeders 
will take out the small quantity of trash that comes in carefully 
picked cotton. (PI. IV.) 
A picker-roll cleaner is necessary to clean cotton that has been care- 
lessly picked and is trashy. (PL V.) Usually only three picker rolls 
are used. These should be run at 175 revolutions per minute, with 
the cotton dropping on a shaker that has a slight vertical motion to 
throw the cotton up and down. A horizontal motion is objectionable 
because it tends to roll and twist the cotton. But twisting may result 
