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 bleachmg 

 agent used was reduced in order to magnify any variations in the 

 results obtained. 



Method (d). — The cotton was boiled two hours in a 10 per cent 

 solution of soda ash and bleached cold in electrohtic clilorine con- 

 taining 2 grams of chlorme per liter. 



Method (e). — The cotton was treated as in (d) except that a 

 chloride hme solution, containing 8 grams of chlorine per hter 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 hom*s 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 13 J hters. 



Method {B). — The cotton was treated as in method (A), except 

 that a solution of electrolized 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 



Bet 



3 



7 



3 



8 



3 



8 



3 



7 



3 

 6 



3 



8 



3 



7 



3 



7 



3 





7 







