Study of the equilibrium ionic forms in salt vapors. concentration of regular and mixed ions in the saturated vapors of systems composed of the halides of alkali metals with a common ion. Electrical conductivity of the saturated vapors of the $\mathrm{KCl}$–$\mathrm{KBr}$, $\mathrm{KCl}$–$\mathrm{KI}$ and $\mathrm{KBr}$–$\mathrm{KI}$ systems