chemical durability of optical glasses was studied. in optical lens fabrication, some detrimental phenomena, such as staining, dimming and latent-scratch may appear on the polished surface of optical glasses. for evaluation of surface deterioration resistance of optical glass, four types of chemical durability tests are carried out' (1) chemical durability to water is evaluated by measuring the weight loss of a polished glass specimen immersed in water where its ph was kept constant: (2) staining resistance is evaluated by measuring the time required for interference color on an ion-exchanged layer to turn bluish when the glass was immersed in water: (3) dimming resistance is evaluated by weight loss of powdered glass immersed in a small quantity of water: (4) latent-scratch resistance is evaluated by measuring the weight loss of a polished glass sample immersed in naoh solution or na/sub 5/p/sub 3/o/sub 10/ solution. on the basis of measurements mentioned above, the chemical durability were related to glass composition