Abstract: Fast-response photochromic boron-free aluminophosphate glasses which have silver halide crystals dispersed throughout the glass comprise, in weight percentages:______________________________________ SiO.sub.2 10 to 17% Al.sub.2 O.sub.3 20 to 29% P.sub.2 O.sub.5 30 to 40% R.sub.2 O 8.5 to 17% R'O 4 to 18% ______________________________________Where R.sub.2 O represents Na.sub.2 O and/or K.sub.2 O; R'O represents CaO and/or BaO, the CaO content being at least 4% if BaO is absent and being from 0 to 7% if BaO is present, while the BaO content is from 0 to 18%; the total of SiO.sub.2 + Al.sub.2 O.sub.3 + P.sub.2 O.sub.5 amounting to not less than 69% by weight of the glass. Preferably the total of SiO.sub.2 + P.sub.2 O.sub.5 + Al.sub.2 O.sub.3 is not less than 72% by weight of the glass. The silver content of the glass, expressed as Ag.sub.2 O, is preferably not less than 0.05%. Refractive index n.sub.D can be corrected to the standard ophthalmic value of 1.523 by additions of TiO.sub.2, ZrO.sub.2 and/or PbO.

Abstract: An apparatus for coating glass with a coating consisting of or containing silicon includes a gas distributor for locating transversely of the path of travel of a glass surface. A gas supply duct supplies coating material in gaseous form and the temperature of the duct is controlled. An elongated open-faced chamber positioned adjacent the glass path of travel communicates along its length with the duct through a gas-flow restrictor that provides gas release from the duct into the chamber at constant pressure along the length of the chamber.

Abstract: A glass surface is modified by maintaining a molten alloy body in contact with the surface, which molten body clings to a locating face which comprises at least two metals which migrate into the glass from the molten alloy body, and which dissolve from the locating face into the molten alloy body as migration proceeds, thereby replenishing the molten alloy body.

Abstract: In the refining zone of a glass melting tank the molten glass is supported on a heat conducting base, such as molten tin, heat is removed from the glass through the base and the depth of glass, length of refining zone and temperature difference between the inlet and outlet of the zone are controlled so that the ratio of return flow to forward flow through the zone is between 1/6th and 1/2.

Abstract: Flat glass advancing along a conveyor in the form of a continuous ribbon or individual sheets, is broken into cullet by applying breaking loads to the glass which put breaking stresses into the glass simultaneously about two axes which are substantially orthogonal to one another.

Abstract: A method of producing clad glass rod of uniform diameter from which an optical fibre is drawn. The rate of drawing of the rod from a glass melt and the diameter of the drawn rod are sensed and the sensed values are fed to a coarse open loop control and a high gain closed loop control which regulate the draw speed of the rod and the movement of a cooling jacket which cools the rod as it is drawn.

Abstract: Apparatus for cutting or scoring sheet material, e.g. glass, with rapid responses to irregularities in the surface of the sheet material and to commands to commence or interrupt a cutting or scoring operation, employs a fluid pressure actuated diaphragm device to impart movement to a cutting or scoring tool, e.g. a cutting wheel, towards and away from the surface to be cut or scored, and means for controlling selectively the pressure acting on each side of the diaphragm. The tool may be supported and guided in a cutter head which incorporates the diaphragm device and which carries supporting means, such as a pair of wheels, for supporting the cutter head on the surface of the material when the tool is retracted. Fluid pressure supply to the diaphragm device and to a separate piston device for applying the cutting load can be controlled by solenoid-operated values. Supply of a cutting fluid to the tool can be similarly controlled.

Abstract: A coating composition for glass fibres intended for use as reinforcement in cementitious products is disclosed, which contains at least one monocyclic or polycyclic aromatic compound having at least three hydroxyl groups on the aromatic ring or (in a polycyclic compound) on at least one of the aromatic rings, together with at least one partially-cured A-stage phenolformaldehyde resin of the water-dilutable resole type.

Abstract: Molten glass is conditioned to achieve a desired thermal distribution suitable for feeding the glass to a forming process. The molten glass is fed to the inlet end of a conditioning zone of a tank and glass flow through the conditioning zone is established in a direction towards a remote outlet from that zone with substantially no return flow. The glass is selectively cooled adjacent the inlet to the conditioning zone to achieve a desired temperature profile through the depth and width of a transverse cross section adjacent the conditioning zone inlet so that on flowing through that zone the further conditioning completes transformation of the glass to a state suitable for feeding to the forming process. The cooling is effected at a position selected in dependence on the temperature distribution within the glass and the required temperature profile by passing cooling fluid through at least one fluid cooled pipe immersed in the molten glass located in the forward flowing body of the glass.

Abstract: An elongated tank body of a glass melting apparatus defines a melting region adjacent its inlet end, a refining region downstream, a conditioning zone adjacent its outlet end and an intermediate zone leading from the refining region to the conditioning zone. The intermediate zone and conditioning zone are substantially narrow relative to the refining region. Flow control means physically slows up the forward flow of the upper levels of glass out of the refining region and into the narrower zones. The refining region and intermediate zone are sufficiently deep for forward and return flow of molten glass to take place. A step is located at the upstream end of the conditioning zone which has a raised base providing a shallow conditioning along which molten glass flows toward the outlet with substantially no return flow.

Abstract: Glass compositions with a particularly high alkali resistance comprise, in weight percentages:______________________________________ SiO.sub.2 45 to 65% ZrO.sub.2 6 to 20% RO 20 to 45% ______________________________________The total of SiO.sub.2 + ZrO.sub.2 + RO being not less than 94% by weight of the glass, where RO represents CaO, in an amount from 20 to 45%, with or without lesser amounts of further divalent oxides of the group consisting of MgO, SrO, BaO and ZnO, the balance (if any) of the composition consisting of compatible constituents such as TiO.sub.2, Al.sub.2 O.sub.3, B.sub.2 O.sub.3, Fe.sub.2 O.sub.3, F.sub.2 and R.sub.2 O, where R.sub.2 O represents K.sub.2 O, Na.sub.2 O or Li.sub.2 O, the amount of any one of these compatible constituents not exceeding 5% by weight. Preferably R.sub.2 O does not exceed 3%.

Abstract: A coating consisting of or containing silicon is produced on glass by moving the glass, at a temperature of at least 400.degree. C, past a coating station to which silane-containing gas is supplied. The gas is released close to the glass surface into a hot zone opening towards the glass surface and at a substantially constant pressure across that surface. Non-oxidizing conditions are maintained in the hot zone, and the coating is produced by pyrolysis of the gas on the glass surface.

Abstract: Alkali-resistant continuously-drawn glass fibers, for use in the reinforcement of cement products, are composed of SiO.sub.2 67 to 82 mol.%, ZrO.sub.2 7 to 10 mol.%, R.sub.2 O 9 to 22.5 mol.% (where R = Na, up to 5 mol.% of which may be replaced by Li or K), F.sub.2 3 to 9 mol.% and Al.sub.2 O.sub.3 (computed as AlO.sub.1.5) 0 to 5 mol.%, the permissible maximum value of the total of SiO.sub.2 + ZrO.sub.2 + AlO.sub.1.5 being on a sliding scale dependent on the content of ZrO.sub.2 and ranging (when F.sub.2 = 9 mol.%) from 89 mol.% when ZrO.sub.2 is 7 mol.% down to 87 mol.% when ZrO.sub.2 is 10 mol.%, the said maximum value being reduced by a further 5 mol.% over the whole scale when F.sub.2 = 3 mol.%. The fiberizing temperature is below 1350.degree. C and the liquidus temperature is at least 40.degree. C below the fiberizing temperature. Preferably, to ensure that the fiberizing temperature is below 1320.degree. C, the said maximum value of SiO.sub.2 + ZrO.sub.2 + AlO.sub.1.5 is further reduced by 1 mol.

Abstract: A predetermined rate of flow of molten glass from a reservoir, for example a glass melting furnace, is maintained by flowing glass from the reservoir to an intermediate vessel in which the glass temperature is fixed in relation to the temperature of glass discharging from the reservoir, continuously developing a control signal representing any change in the quantity of glass in the intermediate vessel, and using that signal to adjust the flow from the reservoir.

Abstract: An interleaving material for separating glass sheets and protecting them from scratching and staining during storage or transit comprises a porous finely divided support material, such as wood flour, impregnated with a weakly acidic material such as an organic acid (e.g. adipic acid) or an acid reacting salt, and fine particles of a chemically inert plastics material, e.g. a methyl methacrylate, preferably of slightly larger particle size than the acid-impregnated support material.

Abstract: Patterned float glass is manufactured by locating in contact with the float ribbon, while it is hot, a shaped molten body of a material for modifying the glass surface. The configuration of the molten body is progenitive of a pattern to be introduced into the glass and ionic migration is engendered electrically between the molten body and the glass in a sequence of defined time periods to produce a pattern of modified glass in the ribbon surface.

Abstract: In a glass melting tank stirrers are provided between the refining and conditioning zones. The stirrers extend side by side across the path of forward glass flow and are driven by a motor so that they rotate about vertical axes out of phase with each other.

Abstract: An elongated locating member is employed to locate a molten body for treating a glass ribbon in contact with a surface of the ribbon. A wettable surface region of the locating member to which the molten body clings is demarcated by a surface layer of a material which is not wetted by the molten body.

Abstract: In a glass melting tank a water cooled barrier extends horizontally across the forward flow of molten glass to control the forward flow towards the working end and a plurality of stirrers, rotatable in phase with each, are arranged side-by-side across the flow path adjacent the barrier.

Abstract: Surface modified glass is produced by method and apparatus in which the glass is contacted with a molten body, for example of a molten metal or molten alloy while the glass temperature is such that it can be modified by migration of cations from the molten body into the glass surface. This cationic migration is electrically induced and the molten material is periodically connected as a cathode with respect to the glass for a preset time sufficient at least partially to deoxidize the molten material. Non-oxidizing conditions may be maintained in the molten material and the electrical action at the interface between the molten body and the glass while the molten body is connected as a cathode causes reduction of at least a proportion of the cations in the glass surface to produce a metallic dispersion.The invention is particularly applicable to the modification of the upper surface of a ribbon of float glass advancing along a molten metal bath.