Triatomic Hydrogen as an Emitter of the Secondary Spectrum

It appears quite probable that some lines in the secondary spectrum of hydrogen may be emitted by an excited ${\mathrm{H}\prime }_3$ molecule formed by the process ${\mathrm{H}\prime }_2$+${\mathrm{H}}_2$→${\mathrm{H}\prime }_3$+H. Thus Richardson thinks that the question of the rival claims of ${\mathrm{H}}_2$ and ${\mathrm{H}}_3$ to his $\mathrm{H}\alpha$, $\mathrm{H}\beta$, $\mathrm{H}\gamma$, bands is unsettled. Allen and Sandeman have found a band system which they definitely ascribe to ${\mathrm{H}}_3$. An attempt was made to verify these results by correlating the variation in the concentration of ${\mathrm{H}}_3^{+}$ ions and presumably of ${\mathrm{H}}_3$ excited molecules with the variation in intensity of the lines.