ELECTRICAL CONDUCTIVITY OF COTTON 451 



fashion from more uniformly distributed hydroxyls, and therefore on 

 any descending curve the conduction of current can be considered to 

 be along more continuous paths. This difference in continuity of 

 moisture paths is sufficient to account for high insulation resistance 

 values on absorption and low values on desorption curves, for each 

 equilibrium moisture content. The actual insulation resistance in 

 any given case depends upon the degree of continuity of such moisture 

 paths and this in turn depends upon the previous treatment of the 

 material. 



Also it seems reasonable to consider that some of the properties of 

 cotton under discussion may be explained to better advantage by the 

 pore theory initially proposed by Urquhart and Williams,^^ since it 

 does not appear that all of the moisture which saturated cotton can 

 absorb is necessarily associated with hydroxyl groups. In con- 

 sidering the pore theory, high insulation resistance values during 

 absorption can be accounted for by a blocking effect of the pore 

 entrances by a few water molecules. This pore blocking effect sug- 

 gested by Peirce ^^ would cause greater discontinuities in moisture 

 paths through the cotton, and therefore higher insulation resistance 

 for a given moisture content. 



Since it is planned to discuss this theory more in detail in a separate 

 paper when experimental data now being secured are available, only 

 the above brief outline is given at this time. 



Acknowledgments are made to Mr. M. H. Quell, Mr. H. S. Davidson, 

 and Mr. G. E. Kinsley for their valuable assistance in securing the 

 data reported in this paper. 



28 Peirce, Jour. Text. Inst., 20, Tl 33, 1929. 



