4 BULLETIN 1184, U. S. DEPARTMENT OF AGRICULTURE. 
USES AND MANUFACTURING QUALITIES OF PIMA COTTON. 
When this country entered the World War in April. 1917, the 
necessity of maintaining a superior air force was evident. Congress 
therefore appropriated $640,000,000 for the development of an ade- 
quate airplane service (8). 
The drain on the material resources of the world, especially upon 
the supplies of flax and linen, had been tremendous, on account of 
the increased production of airplanes by the other nations involved 
in the war. Until January, 1917, nothing but linen had been suc- 
cessfully used for airplane wing covering; but as a result of the 
partial failure of the Canadian flax crop of 1916, the control of the 
Russian flax and linen stocks by a foreign syndicate, and finally 
the capture by the Germans of Riga, the export point for Russian 
flax, the shortage of linen became acute, especially for the United 
States, as the Allies required all their available supplies for their own 
airplanes (8). 
As it required several million yards of cloth to construct the 22,000 
machines provided by the airplane appropriation of 1917. it was nec- 
essary to find a substitute for linen, and as the American Egyptian, 
Sea Island, and Sakellaridis Egyptian cottons seemed the most de- 
sirable substitutes available the United States naturally turned to 
that source to relieve the situation (8). 
Through the cooperation of the Signal Corps of the Department 
of War. the Bureau of Standards, the Bureau of Plant Industry, 
and the Bureau of Markets tests of these cottons were conducted, 
and it was found that the fabric made from any of these cottons 
was above the requirements of the specifications of the Signal Corps 
for airplane cloth. 
The Pima fabric, made of 2 /00s - plain weave 80 by 80, weighing 
4.23 ounces per square yard. 0.77 of an ounce lighter than the speci- 
fications, which is an advantage, was 16 per cent stronger than that 
required (8). 
The tire trade does not require as fine smooth yarns as are needed 
in manufacturing fine goods, and since approximately 85 per cent 
of the Pima cotton produced was used in the tire trade it has been 
assumed that fine yarns can not be made from this variety. But 
the chief requisites' for good spinning qualities are length, strength, 
elasticity, spirality. and fineness of diameter, all of which have been 
remonstrated thoroughly in many instances in the use of Pima 
cotton. Much stress is put upon these qualities by some manufac- 
turers, whose analyses of these characteristics vary slightly, though 
in practically the same ratio. 
A manufacturer reports the results shown in Table 2. which were 
obtained after examining a number of bale samples. 
In figures A, B, and C of Plate 1 3 may be seen sections of Pima, 
Sakellaridis, and Sea Island cotton fibers enlarged 250 times. It 
will be noted that the ends of the fibers are lacking in spirality, 
which is the case with every variety of cotton. 
2 The expression " 2/60s " is read 2-plv sixties, meaning that two sin.de yarns. No. 60 
each, have been twisted together, forming a ply yarn. The expression "80 by 80" indi- 
cates that there are 80 threads per inch both warpwise and fillingwise. 
3 Photographs furnished by the Bureau of Standards 
