Abstract: The decorative vitreous beads of the present invention have a hard, solid, substantially vitreous, unitary body comprised primarily of silica and having a generally spherical form, with the largest dimension being in the range between ⅛ inch to 2 inches. The body by weight comprising 35% to 70% of silica and the remaining ingredients by weight are from 65% to 30% for a total of 100% taken from the group comprising potash, soda, calcia, strontia, alumina, zinc oxide, boric oxide, zirconia, magnesia and potassium. Methods are further disclosed for making the decorative beads comprising mixing together a batch of minerals in powder state comprising by weight 35% to 70% of silica and the remaining oxides by weight from 65% to 30% for a total of 100% taken from a group comprising the oxides mentioned previously. The mixed batch is placed in the container which is inserted into a kiln.

Abstract: The present invention relates to transparent microspheres (i.e., beads) that impart yellow color to retroreflected light. The microsphere preferably comprise titania plus alumina, zirconia, and/or silica and iron oxide, manganese oxide, or mixtures thereof. More particularly, the present invention relates to fused microspheres that impart yellow color to retroreflected light having both transparency and mechanical properties suitable, for example, for lens elements in retroreflective articles.

Abstract: Transparent solid microspheres that contain titania plus alumina, zirconia, and/or silica in a total content of at least about 75% by weight, based on the total weight of the solid microspheres, wherein the total content of alumina, zirconia, and titania is greater than the content of silica.

Abstract: A nonradioactive glass in particulate form adapted for radiation therapy in a mammal comprise a biodegradable rare earth-lithium borate glass material of a specified composition which, upon being subjected to an effective amount of neutron irradiation, will produce a beta or gamma emitting radioisotope, the radioisotope being distributed throughout the glass material, the glass upon being introduced into a body fluid for radiation therapy being adapted to react therewith causing the radioisotope to form an insoluble compound on the surface of the glass material which is retained in the glass material and thereby prevented from escaping from the treatment site. Radioactive glasses and methods for carrying out radiation therapy with such radioactive glasses are also disclosed.

Abstract: Transparent solid microspheres that contain titania plus alumina, zirconia, and/or silica in a total content of at least about 75% by weight, based on the total weight of the solid microspheres, wherein the total content of alumina, zirconia, and titania is greater than the content of silica.

Abstract: A nonradioactive glass in particulate form adapted for radiation therapy in a mammal comprise a biodegradable rare earth-lithium borate glass material of a specified composition which, upon being subjected to an effective amount of neutron irradiation, will produce a beta or gamma emitting radioisotope, the radioisotope being distributed throughout the glass material, the glass upon being introduced into a body fluid for radiation therapy being adapted to react therewith causing the radioisotope to form an insoluble compound on the surface of the glass material which is retained in the glass material and thereby prevented from escaping from the treatment site. Radioactive glasses and methods for carrying out radiation therapy with such radioactive glasses are also disclosed.

Abstract: A double- or single-stranded oligonucleotide comprising one or more respectively inter- or intra-oligonucleotide covalent cross-linkages, wherein the or each covalent linkage consists of an amide bond between a primary amine group of one strand and a carboxyl group of the other strand or the same strand, respectively, said primary amine group being directly substituted in the 2′ position of the strand nucleotide monosaccharide ring, and said carboxyl group being carried by an aliphatic spacer group substituted on a nucleotide or nucleotide analog of the other strand or the same strand, respectively. A method for preparing such oligonucleotides, and nucleotide or non-nucleotide synthons useful for preparing an oligonucleotide of the above kind, are also disclosed.

Abstract: There is a process for producing spherical metal-oxide powder particles. They are used as finely ground raw and filler materials in mineral, ceramic and refractory construction, technical and auxiliary materials, as well as for polishing and grinding agents.

Abstract: The subject invention concerns novel reagents and methods useful for introducing functional groups and labels at multiple sites of a nucleotide. The reagents are useful, for example, in constructing labeled oligonucleotide hybridization probes for detecting the presence of a target polynucleotide in biological or chemical samples.

Abstract: The disclosure describes a method for producing bulk, particulate material that includes solid, generally ellipsoidal particles by dispersing irregularly shaped feed particles including about 60 to 100% by weight of at least one silicate-containing material selected from among wollastonite, alkali feldspar, plagioclase feldspar and nepheline. While maintaining the feed particles in dispersion, they are heated sufficiently to bring about at least partial fusion within at least the surfaces of the particles. This produces a bulk particulate product of which about 15 to 100% by volume is generally ellipsoidal particles. Also described are compositions of matter including solid particles, at least a portion of which are substantially glassy and generally ellipsoidal. At least a portion of these particles have been respectively formed from feed particles composed substantially of at least one silicate selected from among wollastonite, alkali feldspar, plagioclase feldspar and nepheline.

Abstract: The present invention relates to silica materials and particles having surfaces which define an interior. The interior includes interior silicon atoms at least a portion of which is bonded to a substituted or unsubstituted alkyl moiety. In a preferred aspect of the present invention, the silica material also has surface silicon atoms to which are bonded substituted or unsubstituted alkyl moieties. A capillary tube coated on its inner surface with the silica material of the present invention is also disclosed. The silica materials of the present invention are resistant to degradation at high or low pH and are particularly useful as chromatographic stationary phases, especially for use in open tubular liquid chromatography and open tubular electrochromatography.

Abstract: Spherical metal-oxide powder particles are used as finely ground raw and filler materials in mineral, ceramic and refractory construction, technical and auxiliary materials, as well as for polishing and grinding agents. There is a process for producing the powder particles, and there is a process for treating ceramic and refractory residual materials.

Abstract: A process for producing inorganic microspheres (solid spheres or hollow spheres), which comprises pulverizing a material by wet pulverization to an average particle size of at most 5 .mu.m to obtain a slurry of a pulverized powder material, spraying the slurry to form liquid droplets, and heating the liquid droplets to fuse or sinter the powder material to obtain inorganic microspheres.

Abstract: A method for manufacture of glassware with an EM Culture embedded in the glass matrix to improve the palatability of foods or drinks is disclosed. A suitable amount of broth or stock made from fish is mixed with hot water and then a suitable amount of an EM Culture is added to the broth/hot water mixture. The resulting mixture is added to raw materials for glass in a suitable proportion. The mixture is then subjected to aging for a sufficient period of time to have activated the an. EM Culture contained therein. Thereafter, the mixture is melted and formed into a glass article of a desired shape.

Abstract: A method and composition of matter for balancing tire and rim assemblies of vehicles is disclosed wherein the composition of matter has rounded balancing elements of different sizes to line the interior of a tire casing and to move over the lining to offset points of imbalance.

Abstract: Substantially spherical particles of lithium silicates with improved mechanical properties and improved surface quality are provided, which are particularly suited for use as breeding material for tritium. The particles are characterised in that they contain additions of tellurium and/or tellurium compounds.

Abstract: An acid-resistant glass article is provided comprising: about 25-45 wt-% SiO.sub.2 ; about 20-35 wt-% TiO.sub.2 ; less than about 5 wt-% B.sub.2 O.sub.3 ; about 15-40 wt-% of an alkaline earth modifier selected from the group consisting of BaO, SrO, and mixtures thereof; and no greater than about 25 wt-% of an alkali-metal oxide selected from the group consisting of Na.sub.2 O, K.sub.2 O, and mixtures thereof. The glass article is preferably in the form of a microsphere that is adapted for use as a retroreflective element in pavement markings.

Abstract: Glass beads in accordance with the present invention may be constituted of SiO.sub.2, Al.sub.2 O.sub.3, Na.sub.2 O, K.sub.2 O, BaO, SrO, TiO.sub.2, and CeO.sub.2. The glass of which the glass beads is made will generally contain at least 40% SiO.sub.2 as the network former, from about 10 to about 25% Na.sub.2 O and K.sub.2 O as fluxes, from about 5 to about 25% of BaO and/or SrO as a fracture resistance improvement components, a small amount of Al.sub.2 O.sub.3, and--when made from CRT waste--very small amounts of TiO.sub.2 and CeO.sub.2. The glass beads of the invention are suitable for use as reflective elements in roadway markings and as media in shot-peening metal cleaning procedures.

Abstract: The disclosure describes a method for producing bulk, particulate material that includes solid, generally ellipsoidal particles by dispersing irregularly shaped feed particles including about 60 to 100% by weight of at least one silicate-containing material selected from among wollastonite, alkali feldspar, plagioclase feldspar and nepheline. While maintaining the feed particles in dispersion, they are heated sufficiently to bring about at least partial fusion within at least the surfaces of the particles. This produces a bulk particulate product of which about 15 to 100% by volume is generally ellipsoidal particles. Also described are compositions of matter including solid particles, at least a portion of which are substantially glassy and generally ellipsoidal. At least a portion of these particles have been respectively formed from feed particles composed substantially of at least one silicate selected from among wollastonite, alkali feldspar, plagioclase feldspar and nepheline.

Abstract: Glass bubbles for use as fillers in a plastic resin substrate of an electrical printed circuit board are light in weight, low in density, and small in alkali amount leached sufficiently to insure electrical insulation resistance of the substrate, and consist essentially of, by weight, SiO.sub.2 40.0-60.0%, Al.sub.2 O.sub.3 5.0-22.0%, B.sub.2 O.sub.3 1.0-15.0%, CaO 10.0-30.0%, BaO 0-15.0%, MgO 0-10.0%, ZnO 0-10.0%, SrO 0-10.0%, Na.sub.2 O+K.sub.2 O+Li.sub.2 O 0-1.9%, As.sub.2 O.sub.3 +Sb.sub.2 O.sub.3 0-1.54, V.sub.2 O.sub.5 0-10.0%, TiO.sub.2 0-10.0%, and SO.sub.3 0.05-1.7%.

Abstract: Substantially spherical particles of lithium silicates with improved mechanical properties and improved surface quality are provided, which are particularly suited for use as breeding material for tritium. The particles are characterized in that they contain additions of tellurium and/or tellurium compounds.

Abstract: A planar waveguide and a process for making a planar waveguide is disclosed. The waveguide has a layer of doped host material formed on a substrate. The host material is a trivalent material such as a metal fluoride, wherein the metal is selected from the Group III B metals and the lanthanide series rare earth metals of the Mendeleevian Periodic Table. The dopant is a rare earth metal such as erbium. The waveguide has an emission spectrum with a bandwidth of about 60 nm for amplification of an optical signal at a wavelength of about 1.51 .mu.m to about 1.57 .mu.m. The waveguide is made by forming the layer of doped host material on a substrate. The film is formed by evaporating materials from two separate sources, one source for the dopant material and a separate source for the host material and forming a film of the evaporated materials on a substrate.

Abstract: Hollow microspheres produced by the present method each have a hollow interior evacuated of gases to a predetermined pressure. A reflective material layer coats the exterior of each microsphere and, optionally, an outer layer of a protective material is applied over the reflective material layer. Permeant gases are dissolved into glass or plastic frit particles prior to heating of the frit particles to form hollow microspheres having the permeant gases contained therein. The permeant gases are subsequently out-permeated in a non-permeant gas atmosphere to substantially evacuate the interior of each microsphere. The exterior layers of reflective material and protective material are then coated about each evacuated microsphere.

Abstract: Hollow microspheres of ceramic material are formed by a sol-gel technique involving forming and stabilizing an emulsion of an aqueous sol of the ceramic material in an organic phase, followed by dehydration of the stabilized emulsion droplets by extraction using a water-absorbing organic liquid, to form hollow gelled spheres, and finally recovery, drying and calcination of the spheres to the final product. The separation of the emulsion formation and dehydration steps into two distinct stages results in the ultimate formation of microspheres with improved uniformity and size distribution.

Abstract: A method for derivatizing and labeling the 3'-terminus of an oligonucleotide during solid phase synthesis comprising the use of a multifunctional reagent whose preferred structure is shown below. ##STR1## wherein CPG is controlled pore glass beads, Fmoc is 9-fluorenylmethyoxycarbonyl, and the alkylamine contains 1 to 50 carbon atoms.

Abstract: Microspheres for radiation therapy of a mammal which have a non-radioactive isotope which emits beta or gamma radiation of therapeutic intensity upon being irradiated. The microspheres also contain elements which do not become radioactive upon irradiation. The chemical durability of the microspheres is such that they do not release a significant amount of radiation emitting radioisotope into the mammal's system upon administration. Microspheres containing phosphorus or yttrium; and carbon, nitrogen, fluorine, sodium, magnesium, aluminum, silicon, potassium, vanadium, manganese, gallium, niobium, iodine and/or lead.

Abstract: A glass composition for glass bubbles used as reinforcing fillers in plastic resin articles has an improved compressive strength and the reduced alkali amount leached from the glass. The glass composition consists essentially of, by weight percentages, SiO.sub.2 40-59%, R.sub.2 O 2-17%, R.sub.2 O being at least one selected from Li.sub.2 O, Na.sub.2 O, and K.sub.2 O, B.sub.2 O.sub.3 1-25%, RO 5-25%, RO being at least one selected from CaO, MgO, BaO, ZnO, and SrO, RO.sub.2 6-40%, RO.sub.2 being at least one selected from TiO.sub.2 and ZrO.sub.2, Al.sub.2 O.sub.3 0-13%, P.sub.2 O.sub.5 0-3%, and SO.sub.3 0.1-1.0%.

Abstract: In a first aspect, the invention involves a reactive support useful for automated synthesis of oligonucleotides. The reactive support comprises a label moiety (e.g. hapten) covalently bonded via a stable bond to a trifunctional spacer. The labeled trifunctional spacer complex is covalently bonded to a solid support via a cleavable bond. One arm of the trifunctional spacer attaches the solid phase; another arm attaches the label; while the third arm provides a hydroxyl group useful for synthesizing a labeled oligonucleotide. Upon synthesis, the cleavable bond is broken, yielding the labeled oligonucleotide. Methods for labeling oligonucleotides and useful kits are also described.

Abstract: A bead having an exterior surface which is at least partially coated with a material that under illumination and in the presence of air is capable of accelerating the oxidation of organic compounds floating on water. The coated bead is water floatable and has an equivalent diameter of less than about 2 mm, preferably on the order of 10-30 microns. These coated beads can be used to accelerate under illumination oxidation of a floating oil film (e.g. from an oil spill) by dispersing the coated beads in the film and allowing them to be exposed to solar illumination and oxygen.

Abstract: Hollow glass spheres having average densities of approximately 0.10 grams/cc to approximately 2.0 grams/cc are prepared by heating solid glass particles. The glass spheres consist essentially of the following ingredients in the following amounts stated as weight percentages: SiO.sub.2 (50 to 57%); R.sub.2 0(2 to 15%); B.sub.2 O.sub.3 (0 to 20%); S(0.05 to 1.5%); RO(2 to 25%); RO.sub.2 (other than SiO.sub.2) (0 to 5%); R.sub.2 O.sub.3 (other than B.sub.2 O.sub.3) (0 to 10%); R.sub.2 O.sub.5 (0 to 5%); and F(0 to 5%). R represents a metal or an element like phosphorous which combines with oxygen in glass. The sizes of the hollow glass spheres are selected to produce a maximum average strength for a desired average density.

Abstract: Low sodium hollow glass microspheres containing less than about 3 wt. % Na.sub.2 O are produced from aqueous precursors. The method comprisesa) forming an aqueous glass precursor solution or slurry by combining sources of cations contained in the glass, the solution or slurry comprising all of the glass cations in proportions substantially identical to those in the glass,b) forming the solution or slurry into droplets, andc) heating the droplets to form the microspheres.The precursor may also contain surfactants, blowing agents or other known expedients. Nonionic fluorocarbon surfactants are preferred.The droplets may be formed by spraying or any other known technique. The droplets may be spray dried prior to heating step c).

Abstract: The subject invention concerns a novel multifunctional solid support reagent which is useful in solid phase oligonucleotide synthesis. Specifically, the reagent is used in a solid phase oligonucleotide process to chemically modify the 3' terminus of a synthetic oligonucleotide with any chemical functional group. The invention reagent can be used to construct 3' labeled oligonucleotide hybridization probes to detect the presence of a target polynucleotide in biological and clinical samples.

Abstract: A method for the production of inorganic oxide particles by a procedure comprising the steps of dispersing inorganic oxide particles as seed particles in a water-containing alcohol solution thereby preparing a suspension of said seed particles and adding a hydrolyzable and condensable organic metal compound to said suspension thereby effecting growth of said seed particles, which method further comprises causing the presence in said water-containing alcohol solution of an alkylene glycol having 2-8 carbon atoms, in an amount in the range of 1 to 50% by weight, based on the amount of said water-containing alcohol solution.

Abstract: Glass compositions for use in the preparation of glass microspheres and having reduced 2 Pas (20 poise) temperatures comprise 38 to 44% SiO.sub.2, 14 to 22% B.sub.2 O.sub.3, 9 to 16% Al.sub.2 O.sub.3, 22 to 26% CaO and optionally MgO, 0 to 8% Na.sub.2 O, 0 to 2% Li.sub.2 O, 0 to 2% K.sub.2 O and 0 to 1% Fe.sub.2 O.sub.3, the sum of B.sub.2 O.sub.3 and Na.sub.2 O being at least 19%, said percentage by weight.

Abstract: Discrete, free-flowing, ceramic microbubbles consist essentially of at least one of a non-oxide component and an oxide component having diameters in the range of 1 to 300 micrometers and each having a wall thickness of less than 10 percent of the diameter of the bubble. In the process of the invention, a sol precursor and a suitable liquid, referred to as a bloating agent, when added to a bubble promoting medium under proper conditions, provide green gelled microbubbles which after firing are ceramic microbubbles having wall thicknesses less than 10 percent of the diameter of the bubbles. The microbubbles are non-vitreous, sol-gel derived, fine microstructured, uniform, hollow, smooth, and are either essentially all oxide or non-oxide or combinations of both.

Abstract: A manufacturing method for ceramic microspheres including the steps of; mixing an oil which is immiscible with an aqueous solution of a water-soluble metallic compound and which has a boiling point higher than that of water in the aqueous solution; applying ultrasonic vibration to the mixed solution to form a water-in-oil type emulsion; heating the emulsion at a temperature less than a boiling point of water to evaporate free water from droplets in which the water-soluble metallic compound is dissolved and to disperse spherical particles of the water-soluble metallic compound in the oil phase; and thereafter heating the dispersed solution at a temperature higher than the temperature at which the water-soluble metallic compound is decomposed to form a metallic oxide but lower than the temperature at which grain growth in the metallic oxide starts, to evaporate and decompose the oil and to remove the oil therefrom, thereby obtaining the metallic oxide microspheres.

Abstract: A glass frit useful as starting material for the preparation of glass bubbles having an extremely low alkali elution, which has the following composition represented by weight percent.______________________________________ SiO.sub.2 58-75 B.sub.2 O.sub.3 11-25 Na.sub.2 O 3-12.5 ZnO 0-3 K.sub.2 O 0-3 Al.sub.2 O.sub.3 0-3 Li.sub.2 O 0-3 P.sub.2 O.sub.5 0-3 Total alkali metal oxides Sb.sub.2 O.sub.3 0-1 3-15 As.sub.2 O.sub.3 0-1 CaO 5-15 SO.sub.3 0.05-1 MgO 0-3 B.sub.2 O.sub.3 /Na.sub.2 O 1.7-4.

Abstract: A method for preparing nonradioactive microspheres adapted for radiation synovectomy of arthritic joints in a mammal involves forming the microspheres by doping a biodegradable glass material which may be lithium or potassium silicate, lithium or potassium aluminosilicate, lithium or potassium aluminoborate, lithium or potassium germanate or lithium or potassium aluminogermanate with an isotope which may be samarium, holmium, erbium, dysprosium, rhemium or yttrium so that the isotope is chemcially dissolved in and distributed uniformly throughout the glass material. The doped glass material is then treated with an acid wash to produce a thin layer on the surface thereof and heat treated to improve the chemical durability of the glass material by rendering the solubility of the layer lower than that of the underlying glass material.

Abstract: A method for manufacturing synthetic silica glass by reacting methyl silicate and aqueous ammonia, dispersing the silica particles produced in water, solidifying the silica by the addition of methyl silicate and heating, dehydrating, de-solventing, decarburizing and sintering the solid silica to produce a glass product. The sintered glass may be pulverized to produce a powder. The inventive method is easily carried out and avoids the high energy costs of the prior art. The glass product obtained exhibits excellent high temperature viscosity.

Abstract: A radioactive microsphere for radiation therapy of a mammal comprising a biologically compatible glass material containing a beta or gamma emitting radioisotope distributed substantially uniformly throughout the glass. Advantageously, the radioisotope is produced by irradiation of the microsphere.

Abstract: Radioactive microspheres for radiation synovectomy of arthritic joints in a mammal comprises a biodegradable glass material and a beta radiation emitting radioisotope chemically dissolved in and distributed substantially uniformly throughout the glass material. The biodegradable glass material may be lithium silicate, lithium aluminosilicate, lithium aluminoborate, lithium germanate, lithium aluminogermanate, potassium silicate, potassium aluminosilicate, potassium aluminoborate, potassium germanate or potassium aluminogermanate and the beta radiation emitting radioisotope may be samarium-153, holmium-166, erbium-169, dysprosium-165, rhenium-186, rhenium-188 or yttrium-90. Method for preparing such microspheres and for carrying out radiation synovectomy of arthritic joints utilizing such microspheres are also disclosed.

Abstract: A non-porous, substantially hollow, expanded mineral product, such as expanded perlite, is produced by uniformly and indirectly heating ore for about 1 to 30 seconds in an expansion chamber maintained at about 1400.degree. F.-2100.degree. F. to produce uncoated particles which exhibit superior short term and long term density stability characterics in liquid systems, and which may subsequently be coated to provide enhanced density stability characteristics.

Abstract: Thin flakes can be made from a sol of metal oxides by a method analogous to blowing soap bubbles, preferably by directing a laminar flow of air through a narrow, annular orifice. The bubbles can be dried and broken into fragments which are fired to produce refractory flakes that can be incorporated into protective coatings. The resulting coatings can be pearlescent while also affording good resistance to abrasion and to corrosive materials.

Abstract: Hollow glass spheres having average densities of approximately 0.10 grams/cc to approximately 2.0 grams/cc are prepared by heating solid glass particles. The glass spheres consist essentially of the following ingredients in the following amounts state as weight percentages: SiO.sub.2 (50 to 57%); R.sub.2 O(2 to 15%); B.sub.2 O.sub.3 (0 to 20%); S(0.05 to 1.5%); RO(2 to 25%); RO.sub.2 (other than SiO.sub.2) (0 to 5%); R.sub.2 O.sub.3 (other than B.sub.2 O.sub.3) (0 to 10%); R.sub.2 O.sub.5 (0 to 5%); and F(0 to 5%). R represents a metal or an element like phosphorous which combines with oxygen in glass. The sizes of the hollow glass spheres are selected to produce a maximum average strength for a desired average density.

Abstract: Microcrystalline alpha-alumina based ceramic articles comprising at least 60% alumina by weight in which substantially all the alumina is in the alpha phase having a uniform grain structure comprising alpha alumina crystallites with an average crystallite size less than 0.5 micrometer and a density greater than 90% theoretical are disclosed. Ceramic articles particularly useful as high modulus refractory fibers, among other shaped bodies such as beads, flakes, coatings, and shaped or randomly-shaped abrasive particles, are produced from a unique sol-gel process wherein hydroxy iron polymers are utilized to nucleate the alpha alumina transformation. An inherent advantage of the unique process disclosed is the resulting fine grained microstructure which is essential if a ceramic article such as an alpha alumina fiber is to have reasonable strength.

Abstract: Porous, silica-rich shapes have improved strength and abrasion resistance by leaching the precursor glass shape in preconditioned acid having silica ion and at least one common ion that is also present in the precursor glass shape. The precursor glass shapes have shapes such as fibers, hollow fibers, tubes, rods, beads, hollow spheres and plates and compositions having 30-75 volume percent silica and at least 10-65 volume percent nonsiliceous acid extractable components. Preconditioning of the acid solution results from a pretreatment of the acid with compounds that dissociate into the ions when added to the acid solution or with shapes, particles or fragments of glass compositions different from or similar to the glass shape to be leached so long as the glass composition has extractable material to provide the silica ion and at least one common ion.

Abstract: The present invention provides a method of synthesizing amorphous cordierite-forming glasses from organometallic precursors. Either the sol-gel/.beta.-diketonate technique or the amorphous chelating hydroxycarboxylate process can be used advantageously. The method of the present invention can also be used to form 5 component comprised and 2 component comprised amorphous compositions wherein one of the components is an oxide of silicon.

Abstract: A multicomponent ceramic article which can be a fiber or particle comprises a continuous ceramic matrix phase and at least one in situ-generated discontinuous ceramic or metal phase. Particles can include shapes in the form of beads, flakes, granules, and microspheres.

Abstract: Glass microbubbles having, on a weight basis, a composition consisting essentially of 70-80% SiO.sub.2, 8-15% CaO, 3-8% Na.sub.2 O, and 2-6% B.sub.2 O.sub.3, and about 0.2-1.5% SO.sub.3 and having a CaO:Na.sub.2 O ratio of 1-3.5. These microbubbles, which are made of significantly less expensive raw materials than conventional products, can also be made with a higher percent "floaters" and a lower average density. Certain substitutions can be made for at least a portion of each of the first three oxides.

Abstract: A process of manufacturing vitreous beads is disclosed in which feedstock particles of a glass-former composition containing less than 15% by dry weight of sodium and potassium calculated as their respective oxides and containing chemically bound water, are fed through a heating zone in which the particles are vitrified and spherulized and the resulting vitreous beads are cooled. The vitrifiable oxide forming elements of said glass-former composition may be chemically interlinked, and the feedstock may be prepared as a silica-based gel or precipitate having a composition suitable for vitrification into a glass of a desired composition which by virtue of its low alkali content is resistant to hydrolytic attack. By control of the cellulating agent content (bound water and optionally a gas evolving salt radical such as nitrate or sulphate) of the feedstock, and its granulometry, the relative proportions of solid and hollow beads which will be produced in a given spherulizing run can be controlled.