Abstract: A laser system generates a beam consisting of light of two wavelengths, one of which is in the visible spectrum. The light of the other wavelength is ultraviolet and is generated from the visible light as a harmonic of it. The ultraviolet light is focussed, by reflection only, onto a target. Most of the visible light is separated out of the beam by dichroic mirrors but a very small residue is allowed to illuminate the target so that the exact position at which the ultraviolet light impacts the target can be monitored by means of a microscope.

Abstract: In a digitized picture, the orientation of the line is made nearly, but not exactly, parallel to a coordinate axis. Statistical analysis of the grid points or of the lattice points forming the line, preferably the former, gives the position and orientation of the line with high accuracy. Repeated measurements after small displacements of the line allows further improvement of the accuracy. Rectangular objects can be measured by taking differences between positions of opposite edges. The method can be extended to deal with curved lines, areas or the detection and measurement of edge or line features such as angles or properties of arcs. Measurement apparatus for practicing the method is also disclosed.

Abstract: A portable safety container for the temporary storage, transport, and/or disposal of mixtures comprising waste organic solvents comprises a strong open-topped outer shell, such as part of a metal can, having at least one handle, an inner shell of material resistant to chemical corrosion, for example a glass bottle, fixed within the outer shell and having a protruding neck fitted with a hinged lid which remains open when the container is inverted for emptying but which is normally held closed by gravity when the container is upright.

Abstract: A process for preparing pyridine derivatives, particularly dipyridyls which are intermediates for the production of herbicides and photographic and metal treatment chemicals, comprises passing an electrical discharge, preferably a silent electrical discharge of the type used in ozoniser equipment, through pyridine or pyridine derivatives in the liquid or vapour state in the absence of oxygen or oxygen-containing compounds.