operating pressure, lowering current drain, and eliminating sparking. It has been found necessary to isolate the Ba vapor from hot graphite source components for optimum operating..., and evaporated to dryness on a steam bath. The resulting boric acid is dissolved in hot water, decolorized with activated charcoal, filtered, and again evaporated to dryness. The purified... gives a negative test for nitrate ion. The cerium carbonate is isolated by filtering through paper and then dissolved in hydrochloric acid. Evaporation a hot plate is continued...