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BELL SYSTEM TECHNICAL JOURNAL 



textile to air saturated with water vapor. From the evidence given 

 in this paper it is seen that exposure to saturated air causes a reduction 

 in the hysteresis loop area for both raw and water-boiled cotton. 

 This behavior is in contrast to the moisture content-relative humidity 

 relation in which a reduction in loop area is observed for raw, but not 

 for water-boiled cotton. 



Between 11 per cent moisture content (about 88 per cent relative 

 humidity) and saturation, the log I.R. — per cent R.H. relation appears 

 to be nearly linear for raw cotton, and on the desorption curve the 

 relation is linear down to about 45 per cent R.H. For water-boiled 



TABLE III 



Moisture Content and Insulation Resistance Data on Water-Boiled Cotton 



IN Equilibrium with Constant Atmospheric Humidities during 



Absorption and Desorption Cycles at 25° C. 



30IZ Cotton — Sample B 



Equilibrium Relative 

 Humidity at 25° C. 



Moisture Content 



% M.C. log % M.C. 



Insulation Resistance per 

 i-in. Length of 30/2- 

 ply Cotton Thread 



megohms log megohms 



cotton, this relation appears to be substantially linear over the full 

 range investigated, from 60 per cent R.H. to saturation on the absorp- 

 tion curve, and from saturation down to about 40 per cent R.H. on 

 the desorption cycle. Curiously, the second absorption cycles for 

 both raw and water-boiled cotton do not exhibit such a linear relation, 

 although in the range above 90 per cent R.H. it is possible that these 

 second absorption curves join the initial absorption curves and become 

 linear in the upper range. 



These curves emphasize the necessity for systematic treatment of 

 textiles in making electrical measurements under definite humidity 

 conditions, since the hysteresis in the per cent R.H. — per cent M.C. 



