Vitriol

In chemistry, vitriol is an archaic name for a sulfate. The name comes from the Latin word "vitreolum" for glassy, as crystals of several metallic sulfates resemble pieces of colored glass.

Alchemical diagram from Daniel Stolz von Stolzenberg, Theatrum Chymicum, 1614 representing VITRIOL as the alchemical motto Visita Interiora Terrae Rectificando Invenies Occultum Lapidem ('Visit the interior of the earth and rectifying (i.e. purifying) you will find the hidden/secret stone'), found in L'Azoth des Philosophes by the 15th Century alchemist Basilius Valentinus. This is a backronym, sometimes incorrectly said to be the origin of the word "vitriol".

In particular:

• Black vitriol is a mixture of iron(II) sulfate and iron sulfide
• Blue vitriol is copper(II) sulfate pentahydrate
• Green vitriol is iron(II) sulfate heptahydrate
• Oil of vitriol is sulfuric acid
• Red vitriol is cobalt(II) sulfate heptahydrate
• Roman vitriol is copper(II) sulfate pentahydrate
• Spirit of vitriol is sulfuric acid
• Sweet oil of vitriol is diethyl ether (not a sulfate)
• Vitriol with no further qualification often means sulfuric acid
• Vitriol of argile is aluminum sulfate (alum)
• Vitriol of clay is aluminum sulfate (alum)
• Vitriol of Cyprus is copper(II) sulfate pentahydrate
• Vitriol of Mars or vitriol martial is iron(III) sulfate
• White vitriol is zinc sulfate heptahydrate

Many other names have the obvious meaning given that "vitriol" means "sulfate": for example, vitriol of lead is lead sulfate and so on.