Manchester Memoirs^ Vol. Iti. i^igoj), No. ^. 3 



The author has ascertained that cotton mercerised 

 either with or without tension possesses the property of 

 absorbing iodine from solution in potassium iodide and 

 water much more freely than does ordinary cotton. 

 Cotton mercerised under tension absorbs less iodine than 

 that mercerised without tension. A parallel between the 

 rate of absorption of colouring matters and of iodine by 

 mercerised cotton has, therefore, been established. 



If ordinary and mercerised cotton is immersed in 

 20CC. of water to which two drops of a solution of iodine 

 in potassium iodide, corresponding to about o'OOogy^S 

 gram. of iodine, have been added it will be noticed that 

 both samples are coloured very faintly yellowish. The 

 author has found that, if, in the place of using water, 

 aqueous solutions of zinc chloride are employed, the 

 minute quantity of iodine present exhibits quite a 

 remarkable action on the cotton fibres. The strength of 

 coloration of the cotton increases to a certain point with 

 the increase in the strength of the zinc chloride solution ; 

 the shade of the colour alters, and the difference in the 

 strength of coloration between the mercerised and the 

 ordinary cotton increases also with the strength of the 

 zinc chloride solution until loocc. of solution contains gyi) 

 grams of zinc chloride. At this concentration the ordinary 

 cotton remains practically white whilst the mercerised 

 cotton appears a dark navy-blue colour. 



Cottons which have been mercerised with different 

 strengths of caustic soda solutions show with this reagent 

 also a gradation in colour by means of which the 

 degree of mercerisation of a given sample may be 

 ascertained. 



The action of both reagents described above, on 

 cotton treated with mercerising agents other than caustic 

 soda, has also been investigated. The action of sulphuric 



