noun

vitriol

A historical name for certain metal sulfate salts.

The old chemistry book lists copper sulfate as blue vitriol.

Etymology

The name belongs to the Latin family for glass. It refers to the glasslike appearance of the crystals of several metal sulfates.

More examples

Green vitriol is an old name for iron(II) sulfate.
An antique label identifies zinc sulfate as white vitriol.
These vitriols contain different metals but all belong to the sulfate family.

vitriol · vitriols

sulfate: A broader term covering salts beyond those historically called vitriol.