Arc and Spark Stands

The length of the instrument from the slit to the end of the plate holder is about 1.2 metres, and it is supported on a massive base which raises the optical parts about 30 cm above bench level. An optical bar of steel is attached to the base of the instrument, from which it projects about 90 cm it is parallel with the optical axis. The bar serves to carry lenses, an arc and spark stand (Gramont stand) for holding samples, and other ancillary equipment. 

Modern arc and spark stands are enclosed systems constructed so fumes and volatile substances enter an exhaust system and are withdrawn from the laboratory. Electrical connections are shielded, doors have safety interlocks, a focusing lens usually is part of the arc-spark stand, electrodes can be positioned laterally and horizontally by external means, and electrical, gas, air, and water facilities usually are available within the excitation enclosure. 

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