234 BELL SYSTEM TECHNICAL JOURNAL 



cotton, it can be observed by ashing the polarized fiber that the ash 

 Hes largely in those portions which were adjacent to the electrodes 

 and especially to the cathode. The electrical resistance is very un- 

 equally distributed along such a polarized fiber or thread, the positions 

 of maximum resistance depending upon the conditions of polarization.'' " 

 Interruption of the current after polarization leads to a gradual 

 restoration of the original electrical properties and a redistribution 

 of the ash constituents with a speed depending largely on the humidity. 

 Reversal of polarity is accompanied by a rapid drop in insulation 

 resistance, followed upon continued application of voltage in the 

 reverse direction by polarization in the opposite sense. Interruption 

 of the circuit after polarization leaves large potential differences on 

 the opposite ends of the fiber, which persist for several minutes. 

 The cathode region is found to be alkaline in reaction, the anode 

 region acidic. The polarized fiber is therefore a concentration cell. 



The electrolysis of cotton may be carried out experimentally in 

 another way. If cotton yarn is immersed in water in each of a series 

 of cells separated from one another by a parchment paper membrane 

 and a direct current is passed through the cells for some hours, the 

 impurities tend to accumulate near the electrodes, with the develop- 

 ment of acidity at the anode and alkalinity at the cathode, as is 

 usual in the electrolysis of a saline solution. If the samples of cotton 

 yarn be now removed and brought into equilibrium with an atmos- 

 phere of standard humidity, the insulation resistance is found to 

 vary fairly regularly with the original position of the sample in the 

 series of cells, being greatest in some intermediate cell and diminishing 

 toward either electrode. The precise position of the maximum varies 

 with the nature of impurities present in the system. The highest 

 insulation resistance may be many times that of the original cotton. 



Perhaps the most significant evidence of the importance of electro- 

 lytic impurities in silk, wool, cotton, and to some extent other textiles, 

 is the fact that their electrical characteristics can be greatly improved 

 by thorough washing with water though without altering qualitatively 

 the general nature of the electroconducting phenomena which char- 

 acterize them. Fig. 2 illustrates the result of washing upon the 

 insulation resistance of cotton and silk threads. The improvement 

 in insulation resistance of cotton and silk upon washing ranges 

 commonly from fifty to one hundred fold, under any of the commonly 

 prevailing conditions of atmospheric temperature and humidity. This 

 improvement is accompanied by diminution of the ash content, in 

 the case of cotton from about 1.0 per cent to 0.15 or 0.25 per cent. 

 It produces only a slight reduction in the equilibrium moisture content 



