On the Influence of Pressure upon the Spectra of Gases and Vapours

Abstract

HERR G. CIAMICIAN has recently communicated to the Vienna Academy the results of a series of interesting experiments made with a view of investigating the influence of pressure upon the spectra of gases and vapours. From the somewhat lengthy report we gather the following data, which may prove acceptable to those of our readers who are actively engaged in spectroscopic research. The spectra of the three halogens, chlorine, bromine, and iodine, show on the whole the same peculiarities when the pressure is increased. The bright lines become diffused, sometimes a little broader, without, however, changing into bands. Besides this, a continuous illuminated background appears, which increases in brightness with the pressure, and which often overpowers the lines. This is particularly the case with iodine, where, eventually, nothing but a continuous spectrum is seen; while with chlorine and bromine certain lines yet remain brighter than the continuous light. The behaviour of certain lines in the red part of the spectra of chlorine and bromine is remarkable, as they retain their original sharpness and fineness under any pressure.