12 
BULLETIN" 359, U. S. DEPARTMENT OF AGRICULTURE. 
Finally all the samples were blued with 0.001 per cent of blue violet 
acid dye. 
These three methods represent the usual means taken to obtain 
white cotton for spinning, except that the quantity of bleaching 
agent used was reduced in order to magnify any variations in the 
results obtained. 
Method id). — The cotton was boiled two hours in a 10 per cent 
solution of soda ash and bleached cold in electrolitic chlorine con- 
taining 2 grams of chlorine per liter. 
Method (e). — The cotton was treated as in (d) except that a 
chloride lime solution, containing 8 grams of chlorine per liter was 
used for the bleaching agent. 
Method (/). — The cotton was treated as in (d) except that an 
alkaline solution of sodium peroxide equivalent to 15 grams of 
chlorine per liter was used. 
After bleaching, all the samples were blued as in processes (a), 
(b), and (c). The above concentrations of bleaching agent represent 
those used in commercial practice to obtain equal bleaching results. 
Method (A). — The cotton was treated cold for two hours in a 
2-degree 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 13f liters. 
Method (B). — The cotton was treated as in method (A), except 
that a solution of eiectrolized salt, containing 2.87 grams per liter 
of available chlorine was used as a bleaching agent. 
Laboratory samples of the cottons were bleached by methods (a), 
(b),-and (c). The Arizona-Egyptian cotton bleached more easily 
than did the Sakellaridis, and very closely resembled the Sea Island 
in this respect. 
Samples were also bleached of each of the cottons by methods 
(d), (e), and (f). The results obtained by these tests were negative, 
as the treatment was sufficiently severe to have produced the same 
white on all of them. 
Finally, 2-pound lots were treated according to method (B), 
and the results obtained matched against a series of standard whites. 
Table XII shows the results of this comparison. 
Table XII. — Bleached cotton of the respective grades and lots matched against a series of 
standard whites. 
Arizona-Egyptian. 
Sea Island. 
Sakellaridis. 
1 
2 
3 
4 
5 
6 
7 
8 
9 
Set 
3 
7 
3 
8 
3 
8 
3 
7 
3 
6 
3 
8 
3 
7 
3 
7 
3 
7 
