Abstract: A device for controllably delivering a material into an aqueous medium, the device comprising a soluble portion which is adapted, in use, to dissolve in an aqueous medium thereby to deliver into the aqueous medium a material which is retained in the device, the soluble portion comprising a soluble phosphate glass having a P.sub.2 O.sub.5 content of from 40 to 50 mole %, and constraining means which are located in the vicinity of the soluble portion and which are arranged, in use, to constrain a stationary liquid layer between the soluble portion and the constraining means. The invention also relates to a method of controllably dissolving a soluble phosphate glass in an aqueous medium.

Abstract: A device for the controlled release of an active material into an aqueous medium comprises a water soluble capillary tube (11) the bore (12) of which contains an active material (13). Dissolution of the active material is diffusion limited during a delay period while the capillary is dissolving. When dissolution of the tube is complete rapid dissolution of the remaining active material then takes place.

Abstract: A dispenser for use, for instance, as a rumen bolus is a generally cylindrical container (1) for material to be dispersed into the digestive tracts, etc. of a ruminant. The container has a closure (3) held in place by a controlled release glass (CRG) member (5). When this member is dissolved, the closure (3) comes out and the contents are released. The cylindrical container can be formed by a hole in a larger member which has several such holes so that different materials can be released, or materials released at different times.Variants include stacked arrangements in which several dispenser compartments are coupled so that as one is emptied a CRG member is dissolved to release material in the next compartment.In some cases the CRG member acts both as the release device, and as the closure for its compartment, and in others it also acts as a means of linking a number of detachable sections.

Abstract: A porous water soluble glass body is formed by sintering powdered glass, compacted to a predetermined density, at a temperature near the glass softening temperature (T.sub.s). The porous body may be impregnated with an organic material for subsequent release at a rate determined by the glass solubility.

Abstract: A capsule for the controlled release of an active material, e.g. into soil, is described. The capsule comprises an insoluble tubular housing (11) containing a number of water soluble or biodegradable partition walls (13) defining one or more hermetically sealed compartments, (12) filled with the active material (14), e.g. an insecticide. When the capsule is in contact with water or an aqueous medium the partition walls (13) slowly dissolve or degrade thus releasing the active material after a predetermined delay.

Abstract: A device for the controlled release of an active material into an aqueous medium, e.g. body fluids, comprises a water soluble glass container in which the active material is sealed. The container wall has a region of reduced thickness which region dissolves before the remainder of the container wall to release the active material.

Abstract: A therapeutic material is contained in a water soluble glass having a dissolution rate that is distinctly pH sensitive, the ratio of dissolution rates between pH 2 and pH 6 being greater than 60 to 1. The glass incorporates phosphorus pentoxide as the glass former and an alkali metal oxide and one or more alkaline earth metal oxides as glass modifiers.

Abstract: A rumen bolus for supplying a mineral supplement to a ruminant animal comprises a water soluble glass incorporating the mineral and contained in an apertured insert, e.g. plastics, housing. Typically the glass is in the form of tubes or pellets so as to provide a substantially constant dissolution rate.

Abstract: A transparent glass article, e.g., for use as an inspection window in contact with water, including at least a surface layer of a glass which is adapted to dissolve at a preselected uniform rate. Slow dissolution of the glass provides a continuously renewable clear surface.

Abstract: Low concentration standard aqueous solution for analytical purposes is prepared from a water soluble glass body containing the standardizing material. The glasses are phosphorus pentoxide based glasses and provide release rates, e.g. of Na.sup.++, of 0.01 to 100 micrograms per cm.sup.2 per hour.

Abstract: A device for the controlled release of an active material into an aqueous medium comprises a porous sintered body of a water soluble glass (11). The pores of the body are filled with a composition (12) consisting wholly or partially of an active material. The device may be provided with a low solubility coating (13). On immersion in an aqueous medium the glass (11) dissolves to become a sponge-like structure having a plurality of convoluted capillaries and from which the active material is released.

Abstract: A paint composition for inhibiting corrosion of a metal surface includes a powdered sacrificial metal for that surface and a powdered water soluble corrosion inhibiting glass. Typically the paint is a zinc rich paint and the glass is a calcium/zinc phosphate glass.

Abstract: A corrosion inhibiting material comprises a water soluble glass of the calcium oxide/phosphorus pentoxide type which, when in contact with water, releases phosphate ions which inhibit corrosion of adjacent metal surfaces. The glass solubility may be controlled by the incorporation of one or more glass modifying oxides. Advantageously the glass is finely ground and then dispersed in a resin carrier to form a primer paint formulation.The preferred glass forming region of a typical calcium oxide/phosphorus pentoxide system is illustrated in the ternary phase/composition diagram of FIG. 1 of the accompanying drawings.

Abstract: A composite material for the controlled release of an active substrate comprises a relatively insoluble, e.g. polymeric, matrix (11) in which a soluble particulate material (12) is dispersed. When the composite is placed in an aqueous medium dissolution of the particulate material substantially increases the water permeability of the matrix. This effect may be used to provide for the controlled release of an active material into the aqueous medium.

Abstract: Corrosion inhibiting compositions for ferrous and non-ferrous metal surfaces comprise one or more crystalline polyphosphates, e.g. a strontium tripolyphosphate. The compositions have particular application in the preparation of corrosion inhibiting paint compositions. A method of preparation of the polyphosphate materials is described.

Abstract: An animal feed additive comprises a composite of a relatively insoluble binder, a particulate soluble material and an active material. The particulate material is such that it is readily soluble under a particular range of pH conditions, e.g. under said conditions. Dissolution of the particulate material renders the binder water permeable thus permitting release of the active material.

Abstract: A device for the controlled release of an active material into a liquid medium comprises a liquid soluble body having an array of cavities therein containing the active material. The body may be enclosed in a casing of a material having a relatively low dissolution rate and provided with means, e.g. an aperture whereby a portion of the body can be exposed to dissolving attack by the liquid medium. The body is so constructed that the cavity contents are released sequentially and at a predetermined rate.

Abstract: A corrosion inhibiting paint comprises a resin vehicle containing a water soluble glass which, on dissolution in water, releases corrosion inhibiting materials. The glass itself, or the combination of the glass and the paint, are so constituted that conditions of low acidity, i.e. above pH 4.0, are presented to a metal surface to which the print is applied. The glass may contain phosphorus pentoxide as the glass forming oxide together with one or more Group IIA or IIB metal oxides as the glass modifying oxide or oxides.

Abstract: A copper phosphate water soluble glass composition. The composition of the glass may be adjusted so as to release copper at a uniform preselected rate and to produce a desired pH in the resultant solution. In one application of the glass copper may be supplied to an animal from an implant formed from a cupric oxide/phosphorus pentoxide glass which also incorporates one or more glass modifying oxides such as alkali metal oxides and alumina, to control the glass solubility. Suitable glasses comprise 5-55 mole % cupric oxide + alkali metal oxides. 45-75 mole % phosphorus pentoxide, and not more than 15 mole % alumina, where the copper oxide concentration is not less than 5 mole %.

Abstract: A controlled release glass is based on phosphorus pentoxide as the glass forming oxide and an alkali metal oxide as the principal glass modifier. The glass contains a modifying oxide of a material to be released slowly, e.g. one of the oxides of the alkali metal, or an oxide of an alkaline earth metal, an oxide of a metal of Group IIIA of the Periodic Table or a transition metal oxide, depending on the deficiency to be cured.