Abstract
Species of electrical charge carriers in oxide glasses containing neither alkali ions nor transition metal ions is the subject of considerable uncertainty. Two different approaches adopted here made it clear that protons in 
glasses are the charge carriers. One approach adopted is of a change in color by formation of 
, which was caused by injection of the protons of the glass into 
thin film under an electrical field, and the other is of a change in electrical conductivity by H+‐D+ substitution in the glasses.