We can in fact first place the beam of rays of moving positive atomic ions in a plane perpendicular to the axis in which we see the spectral lines emitted by them.
By allowing the positive ions to pass through an electric field and thus giving them a certain velocity it is possible to distinguish them from the neutral stationary atoms.
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Thus at the beginning of 1906 it seemed to be established that the emitters of the spectral series of chemical elements are their positive atomic ions.