The origin, forms, & disappearance of striae in glass are described & illustrated. They are caused by incomplete mixing of the raw materials, which do not have time to become homogeneous either physically by flowing or chemically by dissolving. Artistic forms, such as millefiori, are examples. The origin of striae may be suggested by their location in the glass, form, & colour & by the crystals present. With imperfect fusion & dissolving, honeycombs or cellular glassy occlusions occur in the glass which are the substance from which these striae form. Bubbles are undesirable but are indispensable to homogenisation. Thermal striae occur not only in glass but in every liquid. They are equalised by temperature. Most are not caused by undissolved refractories but by incomplete homogenization of raw materials.
