(under subclass 500.21) Subject matter wherein the membrane comprises a glass.
(1) Note. Glasses are inorganic compositions which solidify from the molten state without crystallizing, to have that molecular disorder characteristic of the glassy state, which have no definite melting point, are incapable in the solid state of permanent deformation, which fracture when subjected to deformation tension and include as components at least one "glass former" material.
(2) Note. Typical glass formers are, e.g., oxides of silicon, beryllium, boron, germanium, phosphorus, vanadium, lead, tin, zinc, zirconium, and titanium, as well as such nonoxide compounds as GeS, metal fluorides, or iodides, and some metallic selenides, tellurides, arsenides, and phosphides. These compositions may also include other oxides devoid of glass forming tendencies, e.g., oxides of alkali metals, alkaline earth metals, and magnesium.
(3) Note. Many ceramic compositions contain primarily slag, the byproduct of metal refining and smelting, which are considered to be glasses.
(4) Note. Neither transparency to light nor the absence of color are necessary for a composition to be considered as a glass for the purpose of this subclass.
(5) Note. Water glass, Plexiglas, and isinglass are not considered to be glass for the purpose of classification in this subclass.
(6) Note. Organic, noncrystalline solid materials, such as
synthetic resins which may referred to as organicglasses, e.g., Plexiglas, are not considered to be glass for the purpose of classification in this subclass. (7) Note. The so-callled metallic glasses or glassy metals, which are amorphous solid forms of metals ar not included herein.