Abstract: The instant invention is directed to the production of highly crystalline glass-ceramic articles demonstrating high intrinsic mechanical strength and toughness containing crystals of canasite and/or agrellite and/or fedorite as the predominant crystal phase. The articles have overall compositions consisting essentially, expressed in terms of weight percent on the oxide basis, of about______________________________________ SiO.sub.2 45-75 CaO 8-30 F 3.5-12 Na.sub.2 O 3-15 K.sub.2 O 0-20 Na.sub.2 O + K.sub.2 O 5-25 B.sub.2 O.sub.3 0-6 Al.sub.2 O.sub.3 0-7 ZrO.sub.2 0-12.

Abstract: This invention is concerned with the production of substantially transparent glass-ceramic articles containing mullite as the predominant crystal phase which can be prepared by crystallizing in situ precursor glasses capable of being melted at temperatures no higher than 1650.degree. C. The inventive articles consist essentially, in weight percent, of 1070% SiO.sub.2, 7-40% B.sub.2 O.sub.3, 14-50% Al.sub.2 O.sub.3, 0-35% RO, wherein RO consists of at least one member of the group in the indicated proportions of 015% MgO, 0-20% CaO, 0-30% SrO, 0-30% BaO, and 0-30% PbO, and 0-30% R.sub.2 O, wherein R.sub.2 O consists of at least one member of the group in the indicated proportions of 0-10% Li.sub.2 O, 0-15% Na.sub.2 O, 0-25% K.sub.2 O, 0-25% Rb.sub.2 O, and 0-25% Cs.sub.2 O, the mole ratio Al.sub.2 O.sub.3 :RO+R.sub.2 O>1.3. Where 0.01-1% Cr.sub.2 O.sub.

Abstract: The present invention provides a method for making porous bodies of magnetic glass and/or crystal-containing materials having magnetic crystals incorporated therein with dimensions less than about 1000A. Preferably, the crystals have dimensions less than 500A such that the porous bodies demonstrate essential superparamagnetic behavior. The method involves preparing a body which, upon heat treatment, will separate into at least two vitreous phases and at least one crystal phase. One of the vitreous phases is etched away leaving a structure remaining which contains said magnetic crystals. When present as fine particles, the porous magnetic bodies are especially suitable for use in biological assays.

Abstract: The present invention is directed to glasses especially suitable as envelopes for tungsten-halogen lamps. The glasses exhibit strain points of at least about 670.degree. C., a coefficient of thermal expansion (0.degree.-300.degree. C.) of 42-45.times.10.sup.-7 /.degree.C. and can be readily melted and shaped utilizing conventional glass melting and high speed tube drawing processes. The glasses consist essentially, in weight percent, of______________________________________ SiO.sub.2 60.0 .+-. 1.5 Al.sub.2 O.sub.3 17.0 .+-. 1.0 B.sub.2 O.sub.3 5.0 .+-. 0.8 CaO 11.4 .+-. 0.8 MgO 7.5 .+-. 0.

Abstract: This invention is directed to the production of transparent photochromic glasses containing silver halide crystals sensitized with copper having base compositions within the alkali metal aluminoborosilicate system wherein at least 0.025% As.sub.2 O.sub.3 and/or Sb.sub.2 O.sub.3 is present in the composition to insure that more than 50% of the copper is present in the Cu.sup.+ state. Where an oxidizing agent is added to the composition, the amount of As.sub.2 O.sub.3 and/or Sb.sub.2 O.sub.3 will be increased to reduce that agent plus insure that more than 50% of the copper is present in the Cu.sup.+ state.

Abstract: The instant invention is directed toward the production of an alkali metal-free glass-ceramic body wherein the predominant, and preferably sole, crystal phase is a calcium fluorophlogopite. The body is strong, chemically durable, exhibits excellent electrical properties, and has a base composition consisting essentially, expressed in weight percent on the oxide basis, of aboutCaO: 5-20MgO: 15-25Al.sub.2 O.sub.3 : 5-20SiO.sub.2 : 35-60F: 5-15which is nucleated with 0.5-3.5% BaO+SrO, consisting of 0-3.5% BaO and 0-2.5% SrO, or, if BaO and/or SrO are absent, with 8-15% TiO.sub.2. The preferred products exhibit a white, translucent appearance and excellent resistance to staining.

Abstract: This invention is directed to the production of glasses having a density of less than 3.26 g/cm.sup.3, a .beta..sub.OH value less than 0.030 mm.sup.-1, and, in a thickness of 2 mm, a transmission of at least about 80% at a wavelength of 4.0 microns and at least about 50% at a wavelength of 5 microns, which have base compositions within the alkali metal oxide-CaO-Al.sub.2 O.sub.3 -GeO.sub.2 -F and/or Cl field consisting essentially, expressed in terms of weight percent on the oxide basis, of______________________________________ GeO.sub.2 36-55 Al.sub.2 O.sub.3 18-31 CaO 10-25 Li.sub.2 O 0-5 K.sub.2 O and/or Na.sub.2 O and/or Li.sub.2 O 7-20 Al.sub.2 O.sub.3 + 1.5 (K.sub.2 O and/or Na.sub.2 O and/or Li.sub.2 .gtoreq.40 F and/or Cl 0.1-4.