﻿4 BULLETIN' 1135, U. S. DEPARTMENT OF AGBICUL.TUBE. 



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 w~ere made 

 except those necessary 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 ways. The amount of invisible 

 waste varies with the amount of moisture in the cotton as w ell 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 w r ork. The cotton also spins and weaves 

 better under proper humidity conditions. 



The humidifiers w r ere 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 wdth a modern auto- 

 matic humidity and temperature regulating s}^stem which controls 

 the humidity at 65 per cent and prevents the temperature from fall- 

 ing below 70° F. 



Twenty-four skeins of 120 yards from each number and twist of 

 yarn w T ere 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 W T as then broken 

 and sized in rotation. This method assures breaking and sizing the 

 yarn of the different lots under identical moisture conditions. . 



