BULLETIN 121, IT. S. DEPAETME^"T OF AGEICULTUEE. 



DIFFERENCES IN LENGTH OF STAPLE. 



These tests were designed to determine approximately the relative 

 amounts of waste in the several varieties and the breaking strength 

 of yarns made from them. The Delta was included so that compari- 

 son of results could be made not only with the ordinary commercial 

 calculations for 1^-inch cotton similarly handled, but also with actual 

 tests of suoh cotton made on the same machines. Each of the five 

 bales tested in this experiment was run on the same machines and 

 with absolutely the same settings, so that the data were strictly com- 

 parable in every way throughout. Notwithstanding the fact that 

 the staple of the different samples varied from l T 3 g to If^ inches, 

 the}^ were all put through the machines with the settings used for 

 1^-inch cotton, because each of the varieties tested is believed under 

 favorable conditions to be in competition with 15-inch Delta staples. 

 The Columbia and Durango were apparently at a disadvantage in 

 this test, because with their shorter staple they would naturally give 

 ar increased percentage of waste. Table I shows, however, that the 

 total picker and card waste was very nearly in proportion to grade, 

 the Lewis apparently being slightly better than the others. 



THE INVISIBLE LOSS. 



The invisible loss, which is shown in Table II, is caused chiefly by 

 loss of moisture and also to some extent by dust and short fibers 

 which are lost in the air during the operation of stripping at the 

 card. There is no appreciable invisible loss after the cotton has 

 passed through the card, as all dust, short fly waste, and excessive 

 moisture have been removed. The percentage of humidity main- 

 tained affects the amount of invisible loss, as the greater the humidity 

 in the mill the more moisture will be retained in the cotton within 

 certain definite limits. There being no humidifying apparatus in 

 the picker, card, and comber rooms at the New Bedford Textile 

 School, the humidity during these tests could not be regulated. It 

 will be seen in Table II that the invisible loss is greater in the low 

 grades, probably because they contain more dust and light trash. 



Table II, 



-Percentage of invisible loss at each machine in the picking and card- 

 ing processes. 





Variety. 





Durango, 

 grade 

 G. M. 



Columbia, 



grade 

 S. G. M. 



Lewis, 

 grade 

 G. M. 



Webber 



No. 1. 

 grade M. 



Webber 



No. ?, 



grade M. 



Pelta 

 blended. 





1 . 875 0. 375 



.58 j .77 

 .071 .144 

 .503 ' 1.31 



1.125 

 .38 



.49 

 .48 



1.75 

 . 7^ 

 .31 



1.49 



2. 00 

 . 52 



(i) 







Finisher picker 



. 57 

 7? 







Card 



0.R2 









Total 



3. 029 2- S09 



2. 475 4. 33 



3.81 

















1 No invisible loss is shown for the Delta cotton up to the card, as this sample was started at that machine. 

 This blend contained one strict low middling, two middling, and two good middling bales. 



