Emily Dickinson Lexicon

VIT'RI-OL, n. [Fr. vitriol; It. vitriuolo; Sp. vitriolo; from L. vitrum, glass; from their crystaline form or their translucency, or perhaps from their color.]

1. In mineralogy, native vitriol is a substance of a grayish or yellowish white color, apple green or sky blue, and when decomposed, covered with an ochery crust. It occurs in masses, disseminated, stalactical, or capillary. Externally, it is dull and rough; internally, it is more or less shining, with a vitreous silky structure. It is called by manufacturers copperas, a name derived from the flower or efflorescence of copper. This substance is seen only in cabinets.
2. In chimistry, a combination of the acid of sulphur with any metallic oxyd; but chiefly green vitriol, or sulphate of iron; blue vitriol or sulphate of copper, and white vitriol, or sulphate of zink. Cyc. Fourcroy.