Abstract: Apparatus for adding materials, especially powdered or granular materials, to a flowing stream, e.g. of molten metal, comprises a nozzle for compressed gas, blowing the additive into the stream, and a detector that detects the stream and switches the flow of additive on and off according to whether the stream is present or absent. The detector is preferably of a non-contact type, sensing radiation from the stream, preferably visible light. The rate of flow of additive can be adjustable. There can be a fail-safe optical detector arrangement monitoring the flow of additive and signalling an alarm if the flow fails or if the nozzle is blocked. The timings of the start and end of the flow in relation to the detection of the metal stream are independently adjustable to ensure that the additive and metal coincide.

Abstract: A work holder for locating a workpiece of arbitrary or irregular shape during treatment comprises a flat horizontal table in which is mounted a two-dimensional array of vertically disposed spaced-apart rods which protrude upwards through the surface and can be moved upwards individually, either manually or by springs or by fluidpressure means such as rams, then clamped in position so that their tips form a cradle conforming to the shape of the workpiece, in which the workpiece rests.