Abstract: A planar optical waveguide comprises at least two cladding layers on a substrate with at least one core layer disposed between the cladding layers. The overcladding layer of the two layers is doped in order to produce a thermal coefficient of expansion close to or equal to that of the substrate in order to reduce the polarisation sensitivity of the device.

Abstract: An anaesthetic vaporizer for supplying an anaesthetic to a patient and having an inlet for receiving carrier gas and an outlet for delivering carrier gas laden with the anaesthetic to the patient. The vaporizer includes a pump having an expandable body, preferably of a metal, and which expands to draw in the liquid anaesthetic from a reservoir through a valving mechanism and which collapses to meter a precise amount of that liquid anaesthetic into a chamber where it is vaporized for introduction into the carrier gas as it passes between the inlet and the outlet.

Abstract: A heavy density depot for lodgement in the remeno-reticulum of a ruminant animal and progressive release of veterinary substance, comprises an elongate body containing the veterinary substance and having an aperture to allow its progressive release, and a domed weight at a leading end of the body to facilitate passage down the animal's oesophagus. The weight is usually outside the body. The construction is particularly compact so maximizing the amount of veterinary substance contained.

Abstract: A body of liquid, such as an aqueous fertilizer mixture, in a tank is stirred and mixed by apparatus which produces a pattern of recirculating flow including a zone of rapid streamline flow in the tank, preferably an upwardly diverging conical pattern and preferably at an eccentric point in the tank. An addition component in fluid state, such as anhydrous liquid ammonia, is injected into the rapidly flowing liquid in a plurality of fine streams from a stationary injection manifold so as to produce an intimate dispersion of finely divided addition fluid at spaced points in the mixture which is immediately carried away from the injection area and widely dispersed in the liquid mixture. When anhydrous ammonia is thus dispersed in a fertilizer mixture containing a suitable reactant, such as phosphoric acid (H.sub.3 PO.sub.

Abstract: A process for extracting methane gas and ammonia from raw material, such as organic waste. The process is carried out in a closed container or digester by anaerobic bacteria. The yield of the conventional anaerobic bacteria digestion process is greatly increased by the novel step of maintaining the space in the digester above the level of the raw material at a pressure below atmospheric during the digestion process.