Halogen n. (Chem.) An electro-negative element or radical, which, by combination with a metal, forms a haloid salt; especially, chlorine, fluorine, bromine, and iodine; sometimes, also cyanogen. See Chlorine family, under Chlorine.
... effect, but that in our case the iodide of potassium is not as effective in awakening the victim as is the sorlus. I do not know whether you have tried that on Terrestrial animals or not. Luckily sorlus is the most plentiful of the halogen groups; we have far more of it than of chlorine, bromine ... — The Black Star Passes • John W Campbell