Mercury electrode test for capacitor paper

When capacitor paper is subjected to electrical stress, large variations in durability are noted from lot to lot. These variations cannot, except in rare cases, be correlated with the usual chemical and physical tests made on such paper. We have indications that the variable characteristics of most significance in regard to durability are probably physical and structural in nature. The mercury electrode test described here is a method of investigating the physical structure of-capacitor paper by which certain striking structural deficiencies may be detected.