Abstract: A device fop detecting liquid incendiaries contained in bottles comprises a flexible cradle, such as a sling of thin rubber sheet (2), mounted between two supports (4); two conductors arranged laterally on the cradle (6), each conductor having a large surface area to thickness ratio; and an electrical circuit including a power source and indication means to provide an indication of the dielectric properties of a bottle placed within the cradle.

Abstract: Semiconductor crystalline materials, e.g. silicon, GaAs, are grown from a melt, e.g. using the Czochralski technique where a seed crystal is dipped into the melt then slowly withdrawn. Rotation of the growing crystal (6) is partly responsible for convective flows within the melt (5). Convective flows are reduced while radial uniformity is improved by subjecting the crystal/melt interface to a shaped magnetic field. This magnetic field is rotationally symmetrical about the axis of crystal rotation, with a component of field parallel to this axis that is less than 500 gauss, preferably less than 200 gauss, with a value above 500 gauss at other parts of the melt. The field may be produced by two superconducting magnet coils (21, 22) spaced apart and arranged co-axially with the axis of crystal rotation.