BULLETIN 1135, U. S. DEPARTMENT OF AGRICULTURE. 
WASTE DETERMINATIONS. 
Accurate weighings were made of the net amount of cotton fed to 
and delivered by each cleaning machine and of the net amount of 
waste discarded by each. From these weighings, the percentage 
of visible, invisible, and total waste was determined. The per- 
centage of waste for each variety is in the description of each test. 
MECHANICAL CONDITIONS. 
The cotton from the bales of different densities of the same variety 
was run under mechanical conditions which conformed to average 
mill conditions for the length of staple used. No changes were made 
except those necessar} r to maintain the desired weight or sizing of the 
stock in process. 
MOISTURE CONDITIONS. 
The moisture conditions under which the cotton is machined affect 
its spinning properties in a number of w r ays. The amount of invisible 
waste varies with the amount of moisture in the cotton as well as with 
differences in the character of the cotton. The moisture content 
depends upon the weather conditions to which the cotton has been 
exposed before reaching the mill and upon the relative humidity 
under which it is machined. Controlling the relative humidity in the 
mill tends to bring the cotton to a certain moisture level and thus 
reduces the varying factor of invisible waste caused largely by fluctu- 
ations in the moisture content of the cotton. Controlling the humid- 
ity also makes possible more accurate weighings or sizings and thus 
gives more even running work. The cotton also spins and weaves 
better under proper humidity conditions. 
The humidifiers were regulated by hand as closely as possible to 
give a relative humidity of 50 per cent in the picker room, 60 per cent 
in the card room, and 70 per cent in the spinning room. At Raleigh, 
N. C, there were no humidifiers in the picker room, but as damp 
weather prevailed at the time the stock was on the pickers the 
humidity was above the desired amount at this point. There was no 
way to dehumidify in any of the tests. On excessively moist or dry 
days, it was not always possible to maintain the humidity conditions 
at the desired level. The actual conditions which prevailed are 
given under each test. 
Samples of the raw stock from the bale, finisher picker lap, card 
sliver, final processes of drawing and roving, and yarn were collected 
for moisture determinations. The results are included under each 
test. 
BREAKING STRENGTH AND SIZING OF THE YARN. 
The yarns were tested for strength and size in the cotton testing 
laboratory at Washington, which is equipped with a modern auto- 
matic humidity and temperature regulating system which controls 
the humidity at 65 per cent and prevents the temperature from fall- 
ing below 70° F. 
Tw T enty-four skeins of 120 yards from each number and twist of 
yarn were reeled and placed on a specially constructed rack and 
allowed to condition at least 24 hours under 65 per cent relative 
humidity before breaking and sizing. Each skein was then broken 
and sized in rotation. This method assures breaking and sizing the 
yarn of the different lots under identical moisture conditions. 
