TESTS OF OFFICIAL COTTON STANDARDS FOR GRADE. 7 
from over equally distributed areas in each section or zone where it 
was produced. This was especially true in the sections west of the 
Mississippi River. The soil and weather conditions often vary con- 
siderably within the same zone, and even if several bales of cotton 
originated from the same locality it is entirely possible for con- 
ditions to affect the tensile strength of the yarn differently. 
The inconsistent variations shown by the tensile-strength test sug- 
gest to the manufacturer who wishes to maintain more uniform 
results in the manufactured product the importance of thorough 
Sais g. . 
In practically every case the yarn made from western upland 
cotton was stronger than that made from the corresponding grades 
of eastern cotton, the difference being from 5 to 9 pounds per skein 
of 120 yards. This observation sustains the prevailing opinion that 
western upland cotton produces a stronger yarn than eastern, because 
its staple is of a heavier body. The fibers are greater in diameter 
and more wiry. For these reasons it is better suited for warp yarns 
than eastern upland cotton. The latter is better suited for filling 
and hosiery yarns because of its softness and pliability. However, 
in the waste cleaning processes western upland cotton lost more than 
eastern upland cotton. 
Figure 4 shows graphically a comparison of the tensile strength in 
pounds per skein of 120 yards each of yarn made from eastern upland 
and western upland cotton. The 22’s warp yarn with 22.23 turns 
per inch, or a twist constant ‘+ of 4.74, was used for this comparison. 
Table III also shows the effect of the different twists per inch in the 
manufacture of 22’s yarn made from the five grades of eastern and 
western upland cotton, respectively. There were used four twist 
constants, namely, 4.20, 4.54, 4.74, and 4.95, which represent, respec- 
tively, 19.7, 21.31, 22.23, and 23.22 turns of twist per inch. 
Contrary to the general belief, the twist constant 4.74, the nearest 
obtainable to 4.75, which is considered as the warp yarn standard for 
upland cotton, did not produce the strongest yarn, showing that the 
points at which twist added strength to the yarn had been exceeded. 
(See also Table V, Textile school tests.) The turns per inch inserted in 
the yarn were verified by actual count after the yarn had been spun. 
While the purpose of these tests was primarily to determine the 
relative percentages of waste in the different grades of cotton, the 
wide variation in the tensile strength served to show that the grade 
and staple of cotton does not always indicate accurately the strength 
of the yarn. Some other characteristics influencing the quality of 
1 Twist constant 4.75 is considered as standard for warp yarns, upland cotton. The twist per inch 
inserted in the yarn will be found by multiplying the square root of the number of yarns by the twist 
constant. 
7875°—17—Bull. 591——2 
