Apr. 19, 1924 
The Salt Content of Cotton Fiber 
295 
The further question arises whether the slightly higher salt content of Pima 
fiber grown in saline soil (Sample B) as compared with that of fiber from non¬ 
saline soil (Sample C) might result in an appreciably greater hygroscopicity, 
which might affect the spinning properties of the fiber. Also, it may be asked 
whether the hygroscopicity is reduced by removal of the water-soluble salts. 
To answer these questions another portion of each sample (B and C) was 
divided into three subsamples of approximately equal weight. These were 
dried at a temperature of 228° F. until no further loss of moisture occurred 
and the dry weight was determined. The samples were then exposed to an 
atmosphere having a relative humidity of 65 to 70, at a temperature of 70° 
F., until they showed no further increase of weight. Their moisture content 
was then computed by subtraction of the dry weight from the final moist 
weight. They were next soaked 24 hours in distilled water, washed thoroughly 
with distilled water to remove the soluble material and dried to constant 
weight. The washed samples were then exposed to a moist atmosphere under 
precisely the same conditions as before, and when they ceased to gain weight, 
their moisture content was again computed. The quantities of water absorber 
hygroscopically, before and after washing, stated as percentages of the dry 
weights of the samples, are given in Table II.® 
Table II.— Dry and moist weights and percentages of water absorbed hygro¬ 
scopically, before and after removal of the Water-soluble salts, of samples of Pima 
cotton grown on saline and nonsaline land at Sacaton, Ariz. 
-,- 
Before washing 
After washing 
Sample and subsample 
Dry 
weight 
Weight 
after 
exposure 
to a 
moist at¬ 
mosphere 
Percent¬ 
age of 
water 
absorbed 
Dry 
weight 
Weight 
after 
exposure 
to a 
moist at¬ 
mosphere 
Percent¬ 
age of 
water 
absorbed 
B—From saline soil: 
1.. 
Grams 
2.86 
Grams 
3.10 
8.4 
Grams 
2.76 
Grams 
2.98 
8.0 
2. 
2.86 
3.10 
8.4 
2.76 
2.98 
8.0 
3...... 
2.86 
3.10 
8.4 
2. 77 
2.99 
7.9 
Average... 
2.86 
3.10 
8.4 
2.76 
2.98 
8.0 
C.—From nonsaline soil: 
1... 
2.87 
3.10 
8.0 
2.80 
3.01 
7.5 
2... 
2.86 
3.10 
8.4 
2.76 
2.99 
8.3 
3... 
2. 85 
3.10 
8.8 
2.76 
2.99 
8.3 
Average_______ 
2.86 
3.10 
8.4 
2.77 
3.00 
8.0 
Comparison of the results, as given in Table II, shows that the capacity of 
Pima cotton fiber for hygroscopic absorption of water is not materially affected 
by removal of the readily water-soluble salts, the unwashed samples having 
absorbed, on the average, only 0.4 per cent atmospheric moisture more than the 
washed samples. It would seem, therefore, that the hygroscopicity of the salts 
present in the unwashed fiber is practically negligible. It is equally clear that 
the fiber produced by plants growing in saline soil (Sample B) had no higher 
capacity for hygroscopic absorption of moisture than the fiber produced by plants 
growing in nonsaline soil (Sample C). * * * 7 
It is concluded that the difficulties said to be encountered in spinning Pima 
cotton under certain conditions of the atmosphere are not attributable to the 
salt content of the fiber. 
8 The writers are indebted to Horace H. Willis, of the Office of Crop Acclimatization and Adaptation 
Investigations, Bureau of Plant Industry, U. S. Department of Agriculture, for the determinations of 
dry and moist weight. 
7 The loss of weight of the samples as a result of washing averages 0.10 gm. or 3.5 per cent of the dry weight 
before washing (Table II). The content of electrolytes in Samples B and C, as given in Table I, column 1 # 
averages 1.65 per cent of their dry weight. It appears, therefore, that electrolytes constituted approximately 
one-half of the water soluble material in these samples of cotton fiber. 
88287—24f-3 
