Red vitriol

Vitriol Vit"ri*ol, n. [F. vitriol; cf. Pr. vitriol, vetriol, Sp. & Pg. vitriolo, It. vitriuolo; fr. L. vitreolus of glass, vitreus vitreous. See {Vitreous}.] (Chem.) (a) A sulphate of any one of certain metals, as copper, iron, zinc, cobalt. So called on account of the glassy appearance or luster. (b) Sulphuric acid; -- called also {oil of vitriol}. So called because first made by the distillation of green vitriol. See {Sulphuric acid}, under {Sulphuric}. [Colloq.] [1913 Webster]

{Blue vitriol}. See under {Blue}.

{Green vitriol}, ferrous sulphate; copperas. See under {Green}.

{Oil of vitriol}, sulphuric or vitriolic acid; -- popularly so called because it has the consistency of oil.

{Red vitriol}, a native sulphate of cobalt.

{Vitriol of Mars}, ferric sulphate, a white crystalline substance which dissolves in water, forming a red solution.

{White vitriol}, zinc sulphate, a white crystalline substance used in medicine and in dyeing. It is usually obtained by dissolving zinc in sulphuric acid, or by roasting and oxidizing certain zinc ores. Formerly called also {vitriol of zinc}. [1913 Webster]