Note 488 — ALUM.
William Johnston translation
[It is scarcely necessary to observe, that many of the compounds of sulphuric acid with metallic oxides were formerly commonly termed vitriols from their glassy appearance; thus, the green vitriol, or briefly vitriol, is the sulphate of the protoxide of iron, white vitriol is sulphate of zinc, and blue vitriol is the sulphate of copper. Sulphuric acid is still more generally known by the name of oil of vitriol and vitriolic acid, from its having been originally obtained by distilling green vitriol.]