TESTS OF OFFICIAL COTTON STANDARDS FOR GRADE. 11 
western Gulf Coastal Plains, and the western Prairie Lands and Pla- 
teau are as follows: 7.58, 7.30, 8.16, 7.14, and 7.85, respectively. 
- These figures are not given, however, as a criterion nor with the infer- 
ence that such close relationship would always prevail. As a matter 
of fact, material differences in the percentage of waste for thesame 
erade often are found in neighboring sections of the country. Anum- 
ber of the large manufacturers early in the cotton season each year 
test carefully various lots from several different sections of the cotton 
belt to determine which cotton is best suited for their use. 
7 
2 ZO 
ie ee pe ltoaat ign) 
—S—westesn|pRaTRIE Laups afp Plateau =| 
EASTERN GULF 
COASTAL PLAINS 
WESTERN GULF _ 
COASTAL PLAINS 
Fig.6.—The combined visible and invisible waste percentages of five grades of cotton from the different 
zones. (Textile school tests.) 
TENSILE-STRENGTH COMPARISONS. 
(Textile-school tests.) 
The tensile-strength tests of the yarn spun from the cotton origi- 
nating in the various zones were made as described on page 6. Table 
_V gives the results of these tests for the different zones and the same 
grades from each zone. No. 22’s yarn was used in each case. Three 
different twist constants were used in order to determine the relative 
tensile strength of yarns made from upland cottons with different 
twists per inch. 
