536 BELL SYSTEM TECHNICAL JOURNAL 



previous paper reference was made to laboratory experiments in which 

 raw (untreated) cotton was washed with distilled water and various 

 aqueous solutions, and sufficient analytical data were given to show the 

 effects of changes in the ash constituents upon the electrical properties 

 of the cotton. 



It is the purpose of this paper to present a discussion of the analytical 

 data obtained in these experiments, together with a possible distribu- 

 tion of the ash constituents as salts occurring in the raw cotton. This 

 distribution is based upon a somewhat unusual consideration of the 

 analytical data. It will be shown that ionic interchange occurs when 

 cotton is washed in aqueous salt solutions, the principal effect being 

 the replacement of Mg++ in the cotton by Ca++ from CaS04 solutions 

 used in washing, or the reverse if the solutions are MgS04. Although 

 these analytical data were secured in an investigation of the electrical 

 properties of cotton, they are the subject of a more general discussion 

 in this paper, since it is possible that they may be of service in the 

 study of other properties of cotton or other forms of cellulose. 



Influence of Ash Constituents on the Electrical Conduction of Cotton.^ 

 A. C. Walker and M. H. Quell. It has been shown that the elec- 

 trical properties of textiles, such as cotton, silk, wool, and cellulose 

 acetate silk, depend to a remarkable extent upon their moisture 

 contents and chemical compositions. In addition, these properties 

 have been considered to depend upon water-soluble, electrolytic im- 

 purities present in the fibres, since the insulation resistance of untreated 

 cotton has been improved very greatly by water washing. 



Evidence will be presented in this paper to show that the improve- 

 ment in d-c. insulation resistance of cotton, secured by washing, is 

 accompanied by a reduction in the inorganic ash content from about 

 1 per cent of the dry cotton weight to a value generally less than 0.3 

 per cent. Data will be given to show that the water-soluble salts 

 present in raw cotton, which constitute about 70 per cent of the ash 

 weight, are principally potassium and sodium salts, and their removal 

 by washing is accompanied by an improvement of between 50 and 100 

 fold in the insulation resistance. Since these salts are largely in- 

 organic electrolytes, this improAement in resistance is termed electro- 

 lytic. A total improvement of between 150 and 200 fold can be secured 

 if the washed cotton is dried under certain conditions. The difference 

 between electrolytic and total improvement is due to changes in the 

 moisture-adsorbing properties of the textile resulting from the manner 

 of drying, and this difference, largely reversible by subsequent ex- 



^ Journal of the Textile Institute, March, 1933. 



