MICROSCOPE IN MANUFACTURES 



raw cotton has been treated and also to the 

 methods of manufacture. 



A very striking experiment may be tried by 

 soaking a few cotton fibres in cuprammonia, a sub- 

 stance prepared by the action of ammonia solution 

 on copper filings. Constrictions occur at fairly 

 regular intervals along the fibre so that, after treat- 

 ment with cuprammonia, the cotton fibres resemble 

 strings of little beads. 



The manufacture of mercerised cotton has become 

 very important of late years. The process is named 

 after its inventor, Mercer, and consists in removing 

 the skin from the fibres, causing them to untwist 

 and, by doing so, to impart to them a lustre of 

 silk. We may make a little mercerised cotton for 

 examination under the microscope by soaking some 

 raw fibres for a short time in a solution of caustic 

 soda or caustic potash and then washing them in 

 water to which a little acid has been added. This 

 will cause the fibres to untwist and also destroy the 

 skin, but we shall probably notice that the fibres 

 have shrunk. In the process of manufacture pre- 

 cautions are taken to prevent this shrinking for then 

 the lustre is much better. We shall also observe 

 that in our mercerised fibres the lumen has become 

 very narrow and it is often broken, here and there 

 are swellings on the outside of each fibre, corres- 

 ponding to the positions of the twists. Mercerised 

 cotton, in addition to its lustre, is stronger and 

 absorbs dyes more easily than ordinary cotton. 



Flax consists of the bast fibres of the fiax plant. 

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