PURIFIED TEXTILE INSULATION 



251 



resistance of the samples. The errors, however, are attributed not to 

 temperature effects on the samples but to variations in relative 

 humidity produced by the temperature changes and the considerable 

 time required for equilibrium to be restored after such changes occur. 

 Another source of error in textile testing is found in the fact that 

 the values of insulation resistance are affected by the humidity 

 condition to which the sample has been exposed prior to the test. 



Fig. 6 — Humidity cabinet for conditioning samples. 



To avoid error from this source, all test samples are conditioned by 

 drying in a desiccator at the approximate temperature of the test 

 tank before being placed in the tank. 



The samples are prepared by winding a number of turns of the 

 textile around the electrodes inserted in the stoppers as shown in 

 Fig. 8. Care is taken not to handle the textile itself during the winding 

 process as perspiration from the hands is likely to contaminate the 

 thread. Samples are left in the tank over night as there is considerable 



