A method for manufacturing glass, including the steps of heat-melting a raw material for producing glass by using a melting furnace having a plurality of gas flow paths while the raw material is levitated from the melting furnace by a gas ejected from the gas flow paths, and performing cooling so as to produce glass, wherein the melting furnace includes a recess portion, at least one first gas flow path configured to eject the gas in the vertical direction into the recess portion, a plurality of second gas flow paths configured to eject the gas in the direction toward the center axis of the melting furnace into the recess portion, the raw material is heat-melted while the raw material is levitated by the gas ejected from the first gas flow path and the gas ejected from the second gas flow paths, and the molten raw material is cooled.

Provided is a method that can manufacture a glass material having excellent homogeneity by containerless levitation. With a block (12) of glass raw material held levitated above a forming surface (10a) of a forming die (10) by jetting gas through a gas jet hole (10b) opening on the forming surface (10a), the block (12) of glass raw material is heated and melted by irradiation with laser beam, thus obtaining a molten glass, and the molten glass is then cooled to obtain a glass material. Control gas is jetted to the block (12) of glass raw material along a direction different from a direction of jetting of the levitation gas for use in levitating the block (12) of glass raw material or the molten glass.

Provided is a method that can manufacture a glass material having excellent homogeneity by containerless levitation. With a block (12) of glass raw material held levitated above a forming surface (10a) of a forming die (10) by jetting gas through a gas jet hole (10b) opening on the forming surface (10a), the block (12) of glass raw material is heated and melted by irradiation with laser beam, thus obtaining a molten glass, and the molten glass is then cooled to obtain a glass material. Control gas is jetted to the block (12) of glass raw material along a direction different from a direction of jetting of the levitation gas for use in levitating the block (12) of glass raw material or the molten glass.

Provided is optical glass containing, in terms of mol % of cations: 10 to 60% of a La.sup.3+ component; more than 0% and up to 75% of a Ga.sup.3+ component; and 5 to 75% of a Nb.sup.5+ component, in which a total amount of the La.sup.3+ component, Ga.sup.3+ component, and Nb.sup.5+ component is 60 to 100%.

A large sized opaque quartz glass ingot having an excellent heat ray shielding property, an outstanding light blocking property, high mechanical strength and small roughness of a baked finished smooth surface. The shape of bubbles inside the quartz glass are almost complete spheres and the average particle size of the bubbles is 1 ?m or less, such that the strength of the opaque quartz glass ingot is increased as the stress concentration at the edges of the bubbles is eliminated and an increase of surface roughness caused by baking is alleviated.

Provided is a glass composition that exhibits greater Faraday effect than ever before. A glass composition contains 48% or more of Tb.sub.2O.sub.3 (exclusive of 48%) in % by mole.

One aspect relates to a process for the preparation of a quartz glass grain, including providing a silicon dioxide granulate from a pyrogenically produced silicon dioxide powder, making a glass melt out of silicon dioxide granulate, making a quartz glass body out of at least part of the glass melt and reducing the size of the quartz glass body to obtain the quartz glass grain. One aspect further relates to a quartz glass grain which is obtainable by this process. One aspect further relates to opaque quartz glass bodies, which are obtainable by further processing of the quartz glass grain.

A phosphate-based glass fertilizer and a method for producing the same are provided. The glass fertilizer and a glass blend from which the glass fertilizer is obtained, have a composition that includes P.sub.2O.sub.5 with a molar proportion within the range between 40% and 50%, K.sub.2O with a molar proportion within the range between 8% and 17%, CaO with a molar proportion within the range between 15% and 25%, Al.sub.2O.sub.3 with a molar proportion within the range between 3% and 10%, and Na.sub.2O with a molar proportion within the range between 8% and 17%, with respect to the combined total molar amount of components that constitute the composition.

Embodiments of the present invention pertain to antimicrobial glass compositions, glasses and articles. The articles include a glass, which may include a glass phase and a cuprite phase. In other embodiments, the glasses include as plurality of Cu.sup.1+ ions, a degradable phase including B.sub.2O.sub.3, P.sub.2O.sub.5 and K.sub.2O and a durable phase including SiO.sub.2. Other embodiments include glasses having a plurality of Cu.sup.1+ ions disposed on the surface of the glass and in the glass network and/or the glass matrix. The article may also include a polymer. The glasses and articles disclosed herein exhibit a 2 log reduction or greater in a concentration of at least one of Staphylococcus aureus, Enterobacter aerogenes, Pseudomonas aeruginosa bacteria, Methicillin Resistant Staphylococcus aureus, and E. coli, under the EPA Test Method for Efficacy of Copper Alloy as a Sanitizer testing conditions and under Modified JIS Z 2801 for Bacteria testing conditions. In some embodiments, the glass and articles exhibit a 2 log reduction or greater in a concentration of Murine Norovirus under Modified JIS Z 2801 Test for Viruses testing conditions.

Provided is a glass composition that exhibits greater Faraday effect than ever before. A glass composition contains 48% or more of Tb.sub.2O.sub.3 (exclusive of 48%) in % by mole.