10 
BULLETIN 366, U. S. DEPARTMENT OF AGRICULTURE. 
BLEACHING OF YARNS. 
The material used in these bleaching tests consisted of yarn made 
from the following samples of cotton : 1 and la, 2 and 2a. Samples 
1 and 2 had been fumigated, and samples la and 2a were nonfumi- 
gatecl. 
All four samples were treated as follows : Boiled for two hours in 
10 per cent solution of soda ash at atmospheric pressure, rinsed until 
free from alkali, then divided into two lots, each lot containing one- 
half of each of the above four samples. One lot was bleached by 
method A, the other by method B, as follows : 
Method A. Treated cold for two hours in a 2° twaddle solution of 
bleaching powder, containing 5.82 grams of chlorine per liter, rinsed 
with cold water, soured with 2 per cent solution of acetic acid, 
rinsed and antichlored in a 2 per cent solution of sodium bisulphite 
30 minutes, then finally rinsed and blued in water containing 1 gram 
of vat blue in each 13 J liters. 
Method B. Treated as in method A, except that a solution of elec- 
trolized salt containing 2.87 grams per liter of available chlorine 
was used as the bleaching agent. 
The tensile strength and the number of the yarn of all four samples 
were taken before and after treatment with bleach A and bleach B 
with the results as shown in Table VII. 
Table VII.— -Tensile strength of yarns before and after bleaching. 
Grey. 
Bleach A. 
Bleach B. 
Sample 
No. 
No. of 
yarn. 
Skein 
breakage, 
60 yards. 
Single- 
thread 
breakage. 
No. of 
yarn. 
Skein 
breakage, 
60 yards. 
Single- 
thread 
breakage. 
No. of 
yarn. 
Skein 
breakage, 
60 yards. 
Single- 
thread 
breakage. 
1 1 26.4 
la I 26.4 
2 i 41.5 
2a 41.5 
44.8 
45.7 
42.4 
43.2 
10.9 
10.9 
9.8 
9.8 
29.2 
29.2 
47.2 
47.2 
36.8 
39.4 
27.7 
29.3 
8.7 
8.9 
7.9 
8.0 
29.4 
29.4 
46.5 
46.5 
44.1 
43.8 
34.6 
39.0 
10.4 
9.7 
8.9 
9.1 
In this table the tensile strength x is given in pounds for the skein 
breaks and in ounces for the single-thread breaks. The skeins were 
taken from the same bobbins of which the single threads were tested. 
From the comparisons of these figures it will be seen that the dif- 
ferences in strength between the fumigated and nonfumigated cotton 
are so small that it would be unsafe to say that these yarns contained 
in them any substance such as acids that would reduce the tensile 
strength of the yarn by releasing the bleaching agent too rapidly. 
DYEING OF YARNS. 
Portions from all of the four samples of yarns, namely, 1, la. 2, 
and 2a, were bleached according to method A and method B, except 
that they were not blued. Instead some of the portions were dyed 
pink and some were dyed blue with both direct and basic dyes. 
1 See footnote, p. 6. 
