IMPROVED COTTON AIRPLANE FABRIC. 
47 
Having applied the usual tests on the doped cloths, further in- 
vestigations were made to determine the behavior of these cloths 
when subjected to continual load as was done in the case of the mer- 
cerized fabrics. Yarn mercerized cloth of Specifications 16,005-A, 
made from American Egyptian cotton, was used for this test, the 
results of which are given below : 
Table 15. — Behavior of doped cloths under continual leading. 
Time of stressing at— 
70 per 
cent. 
80 per cent. 
90 per cent. 
Varnish A 
H. m. s. 
12 
24 
H. m. s. 
10 (Broke.) 
31 (Broke.) 
H. m. s. 
2 30 (Broke.) 
3 40 (Broke.) 
The above table is supplemented by figure 23. The conclusions 
drawn from these results are that the fabrics are unreliable when 
subjected to continual stress that is greater than TO per cent of the 
breaking strength determined by the method described in the Signal 
Corps Specifications. 
SUMMARY. 
These tests showed no wide differences in the amount of waste 
discarded by the three varieties of cotton ; the Pima American Egyp- 
tian cotton showed a waste percentage of 29.09; Sea Island, 26.70; 
and high-grade Sakellaridis-Egyptian, 27.07. 
Sakellaridis-Egyptian cotton gave the strongest yarn and cloth, 
a general average of all of the results showing a superiority of about 
12 per cent over the Sea Island and the American-Egyptian. 
It was found that the twist recommended by the Signal Corps 
Specifications for 80's and 3/80's yarns was excessive, the best re- 
sults being obtained by a combination of twist multiples 3.83 in the 
singles with 3.63 in the ply. 
Of the several weaves tested, the plain weave was found to be the 
most practical. 
Piece mercerization was found to be superior to yarn merceriza- 
tion because it allowed increased quantity and uniformity of pro- 
duction while decreasing its cost ; at the same time it conserved labor, 
material, and transportation facilities. It also tended to reduce and 
equalize the stretch in the warp and filling without materially chang- 
ing its strength per unit of weight. 
Doping changed the stretch-stress qualities of the cloth in quantity 
only. Nitrate dope gave slightly superior physical properties to the 
