MANUFACTURING TESTS OF COTTON 
visible, that which results in a change in weight caused by loss or 
gain in moisture, or by small particles passing off in the air. The 
amount of this invisible waste is affected by the character of the 
cotton in process, by outside weather conditions, and by the tem- 
perature and relative humidity of the room in which the test is 
conducted. 
The percentage of waste on each machine is based on the. net 
weight fed to that machine. The net weight fed to the cards ,s less 
than the weight fed to the pickers by the amount of waste removed 
by the pickers. The percentage of total waste removed is not 
obtained, therefore, by adding the waste percentages for pickers 
and cards. For example, follow the computations for grade No. 
3 (eastern cotton) in Table 3. For every 100 pounds oi raw cotton 
fed to the pickers, 1.50 pounds (1.5 per cent) of viable waste were 
removed and 98.41 pounds of cotton delivered, leaving 0.09 pound 
(0.09 per cent) not accounted for and designated as invisible loss. 
The total waste on the pickers is therefore 1.59 per cent. 
The 98.41 pounds delivered from the pickers were fed to the cards 
which removed 4.47 pounds (4.54 per cent) of waste and delivered 
94.85 pounds of cotton, making a total of 99.32 pounds. This 
latter figure exceeds the weight fed by 0.91 pound (0.92 per cent 
of the quantity fed to the cards). This 0.92 per cent is called in- 
visible gain. 
Combining the pounds of visible waste (1.50 + 4.47), dividing it 
by 100 (pounds fed to the opener), and multiplying this result by 100 
gives the percentage of total visible waste removed. Total visible 
waste removed by the pickers and cards is 5.97 per cent, an amount 
slightly smaller than the sum of the visible wastes (6.04 per cent) 
recorded in Table 3 as from pickers and cards. 
The total invisible waste is figured in a manner similar to that 
used for determining the total visible waste. Note that there was 
a loss of 0.09 pound on the pickers and a gain of 0.91 pound on 
the cards. Therefore, 0.91 pound gain on cards minus 0.09 pound 
loss on pickers equals a net gain of 0.82 pound, which, based on 
100 pounds fed to opener, is 0.82 per cent again. The greater por- 
tion of this gain on the card is due to the fact that approximately 
60 per cent relative humidity is maintained in the card room, 
whereas approximately 50 per cent relative humidity is maintained 
in the picker room where the preceding process takes place. 
The percentage of total visible waste from each grade of the east- 
ern and western cottons is given in Table 4. 
Table 4. — Percentage of total visible waste from pickers and cards, by grades of 
eastern and western cottons 
Type of cotton 
• 
Grade 
1 
2 
3 
4 
5 
6 
7 
8 
9 
Eastern 
Per 
cent 
5.41 
5.58 
Per 
cent 
5.76 
5.22 
Per 
cent 
5.97 
6.07 
Per 
cent 
6.04 
6.48 
Per 
cent 
7.55 
7.43 
Per 
cent 
8.03 
8.13 
Per 
cent 
10.44 
10.27 
Per 
cent 
11. 32 
12.41 
Per 
cent 
14.40 
14 47 
Western 
5.50 
5.49 
6.02 
6.26 
7.49 
8.08 
10.36 
11.86 
14 44 
