vapor is quite transparent to visible light and also to the near ultraviolet, with the exception of its striking absorption at X 2537 and 1849 A., which are the wave-lengths of mercuryresonance.According to R. W. Wood1 a beam of X 2537 A. is reduced 50% in intensity in passing through a 5-mm. layer of mercury vapor at room temperature (p = ca. 0.001 mm.). Wood has also described certain experiments which demonstrate this strong absorption in a spectacular manner.Thus, a quartz flask, evacuated except for mercury vapor at room temperature, was photographed with mercury resonance radiation, with the result that the flask appeared to be perfectly opaque. Again mercury resonance radiation was allowed to fall on a barium platinocyanide screen, which fluoresced visibly. When air was bubbled through mercury at room temperature in an open bottle placed between the source and the screen, the vapor was observed to cast dense shadows on the fluorescent background.The latter experiment, with a convenient source of mercury resonance radiation, affords an impressive demonstration. The source used by Wood {loc. cit.) consisted of a quartz bulb filled with mercury vapor and placed in the exit beam from a quartz monochromator set at X 2537 A. The vapor, excited by absorption of the core of the narrow band at X 2537, re-emitted practically pure resonance radiation, which was used in the above-described experiments.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.