8 BULLETIN" 366, U. S. DEPAETMEXT OE AGRICULTURE. 



which these samples were taken being previously referred to as lot 

 No. 1. In a like manner 2 and 2a represent the 1^-inch fumigated 

 and nonfumigated cotton previously referred to as lot No. 2. Sam- 

 ples 8 to 15, inclusive, were selected from Peruvian cotton received 

 from a manufacturing company. The cotton in samples 1, 2, 8, 9, 

 12, and 13 was fumigated with hj^drocyanic-acid gas. 



BLEACHING OF EAW COTTON. 



Samples of Nos. 2 and 2a were bleached by treating as follows: 



Method a. Not scoured. Bleached with a. solution obtained by the 

 electrolysis of salt containing 0.5 gram of chlorine per liter. In 

 future this solution will be designated as " electrolytic chlorine." 



JMethod &. Scoured in a solution containing 1 gram of soda ash 

 in each 10 cc. then bleached as in a. 



Method c. Treated with 2 per cent acetic acid and bleached as in a. 



Finally all the samples were blued with 0.001 per cent of blue- 

 violet acid dye. 



Methods «, &, and c are the usual precedes for obtaining white 

 cotton for spinning except that the usual quantity of bleaching agent 

 used was reduced in these tests in order to magnifj^ any variation in 

 the results obtained. No differences in the results of any of the 

 methods on the two samples were apparent, which indicates fumi- 

 gating the cotton with hydrocyanic-acid gas had no appreciable effect 

 upon the bleaching qualities of the cotton used in any of the tests. 



To test the effect of fumigation on the various bleaching agents 

 commonly used the following tests were carried out on samples No. 2, 

 2a, and 8 to 15, inclusive : 



Method d. The cotton was boiled two hours in a 10 per cent solu- 

 tion of soda ash and bleached cold in " electrolytic chlorine " contain- 

 ing 2 grams of chlorine per liter. 



Method e. The cotton was treated as in d except that chloride of 

 lime solution containing 8 grams of chlorine per liter was used as 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 of the samples were blued as in 

 methods a, &, and c. 



The concentrations of bleaching agent are similar to those used 

 in practice to obtain equal bleaching value. Close examinations were 

 made of the samples by constructing a sample sheet with the differ- 

 ent samples placed thereon for comparison. This comparison gave 

 no indication that fumigation of cotton alters the bleaching value. 



All of these tests were carried out on all of the samples of cotton. 



To confirm these results, five 1-pound samples of Nos. 2 and 2a 

 were treated by method d^ the following details being observed in 

 connection with the bleaching : After scouring, the cotton was rinsed 



