20 BULLETIN" 591, U. S, DEPARTMENT OF AGRICULTURE. 
solution for 43 minutes, after which they were rinsed freely in cold 
water, soured in a 1 per cent solution of acetic acid, and rinsed 
again. As there was still a slight trace of chlorine, the goods were 
treated in a 2.5° Twaddell solution of hyposulphite of soda at 22° C. 
for 30 minutes. They were then rinsed freely in cold water and 
dried. 
This method does not take into consideration the actual time that 
would be required to bleach the different yarns made from the differ- 
ent grades of cotton. The yarns were all treated under identical 
conditions, and at the same time. The lower grades eould have been 
bleached more satisfactorily if the factors of time, strength of bleach 
liquor, and temperature had been altered. The treatment of all the 
material in the same way, however, gave a satisfactory basis for 
comparison. 
These tests substantiated the following conclusions reached in the 
tests made in the commercial bleachery: The yarns made from 
Middling Fair and Good Middling were practically identical in color 
after bleaching; the yarns made from Middling were not quite as 
glossy or " bloomy" in their appearance, but for commercial pur- 
poses produced satisfactory results; the yarns made from Low 
Middling gave a slightly slaty color when compared closely with the 
higher grades; and the yarns made from Good Ordinary did not 
bleach satisfactorily, i. e., under the same conditions, in that they 
had a decided slaty bluish cast when compared closely with the yarns 
from the Middling cotton or that of better grades. 
While these tests were in progress, moisture determinations were 
made from time to time. Bleaching, calculated on a dry basis, 
caused an average loss in weight for the eastern cotton of 4.69 per 
cent in the textile school test and 5.14 per cent in the commer- 
cial test. 
The average loss in weight due to bleaching of the western cotton 
was 4.78 per cent in the textile-school test and 5.24 per cent in the 
mill test. This difference probably was caused by the 12-hours 
caustic-soda boil under pressure in the mill tests. Several different 
concentrations of bleaching liquor were used in the textile-school 
test; namely, 1, 2, 3, and 4 grams per liter of chlorine. There was 
practically no difference in weight losses due to bleaching. 
The loss in tensile strength due to the bleaching processes was 
12.25 per cent in the eastern cotton, and 16.40 per cent in the western 
cotton. These results were influenced somewhat by a slight differ- 
ence in the moisture content, but this difference was such that it 
would serve further to increase the loss in the western cotton. The 
results seem to indicate that in the bleaching processes chemicals 
act more readily on upland cotton grown west of the Mississippi 
River than on corresponding grades of eastern upland cotton, because 
