Manchester Memoirs, Vol. Hi. (1907), No. % 



IL New Reactions for the Characterisation of 

 Mercerised Cotton, 



By Julius Hubner, M.ScTech., F.I.C. 



(Read and received November 26th, igoy.) 



Although thoroughly mercerised cotton fibres exhibit 

 very distinct microscopic characteristics (Hubner and 

 Pope, Jourjial Soc. Chem. Ind., Vol. XXIII., p. 404), on 

 examining fibres taken from mercerised fabrics it will be 

 found exceedingly difficult, in many instances, to say with 

 certainty whether the goods have been mercerised or not. 

 This may be due to incomplete penetration of the fibre 

 by the soda solution, to the application of certain finish- 

 ing operations after mercerising, and to other causes. 



So far no reliable chemical reaction for the characteri- 

 sation of mercerised cotton is known. 



The author has found on immersing mercerised and 

 ordinary cotton in a solution of iodine in saturated 

 potassium iodide solution for a few seconds, and after- 

 wards washing with water, that the colour of the mer- 

 cerised cotton quickly changes to a blueish-black whilst 

 the ordinary cotton becomes lighter in colour and changes 

 to a brownish-chocolate shade. After further washing 

 the ordinary cotton becomes white whilst the mercerised 

 material remains a blueish-black colour, which fades very 

 slowly on prolonged washing. The reaction proceeds 

 still more distinctly and more slowly if, in place of water, 

 a 2 per cent solution of potassium iodide in water is used 

 for washing the cotton after immersion in the reagent. 

 It will then be noticed that after 5 or 6 washings the 



December 18 th, 1907 ^ 



