90 



TEXTILE FIBRES. 



amount varying with the state of the weather. In other words, cotton 

 in its ordinary marketable condition would lose moisture in the course 

 of manufacture about 5 per cent., and afterwards the yarn made from 

 it, exposed for some time to a Lancashire atmosphere, would regain from 

 2 to 4 per cent, of moisture. 



Fig. 64. Sea Island cotton seed fibres. 



Out of a number of tests recently made with cotton as bought, the 

 following percentages of moisture (over and under the standard) were 

 obtained, the standard being 8J per cent, over absolute dryness : 



Over. 

 1-5 

 2-0 



'7 



5 



Under. 

 2 

 5 

 5 



8 



Over. 



2-3 

 8 

 2 



2-4 



Under. 

 1 

 2 



These are fair moisture results. But cotton is sometimes sold with 

 much more moisture than these figures show. 



Chemical Properties. Cotton fibres consist of cellulose associated 

 with some 3 per cent, or less of substances (including colouring matter, 

 pectin, wax O'l per cent., and albuminous matter) which can be readily 

 removed from the fibre. 



Cellulose is a compound of carbon, hydrogen, and oxygen, having 

 the chemical formula n (C 6 H 10 5 ), and belonging to the carbo-hydrates. 

 In a pure state cellulose is tasteless and odourless. It is combustible. 

 Smouldering cotton gives off the peculiar odour of acrolein. Cellulose 



