Vitriol
Vitriol is the general chemical name encompassing a class of chemical compounds comprising sulfates of certain metalsoriginally, iron or copper. Those mineral substances were distinguished by their color, such as green vitriol for hydrated iron sulfate and blue vitriol for hydrated copper sulfate.
These materials were found originally as crystals formed by evaporation of groundwater that percolated through sulfide minerals and collected in pools on the floors of old mines. The word vitriol comes from the Latin word vitriolus, meaning "small glass", as those crystals resembled small pieces of colored glass.
Oil of vitriol was an old name for concentrated sulfuric acid, which was historically obtained through the destructive distillation of vitriols. The name, abbreviated to vitriol, continued to be used for this viscous liquid long after the minerals came to be termed "sulfates". The figurative term vitriolic in the sense of "harshly condemnatory" is derived from the corrosive nature of this substance.
| Vitriol | Chemical | Comment | Formula | Image |
| Black vitriol | Sulfate • Heptahydrate | SO4·7H2O | ||
| Blue vitriol/Vitriol of Cyprus/Roman vitriol | copper sulfate | pentahydrate | CuSO4·5H2O | |
| Green vitriol/Copperas | iron sulfate | heptahydrate | FeSO4·7H2O | |
| Oil of vitriol/Spirit of vitriol | sulfuric acid | acid | H2SO4 | |
| Red vitriol | cobalt sulfate | heptahydrate | CoSO4·7H2O | |
| Sweet oil of vitriol | diethyl ether | Not a sulfate, but can be synthesized from sulfuric acid and ethanol | CH3-CH2-O-CH2-CH3 | |
| Vitriol of argile/Vitriol of clay | aluminium sulfate | alum | Al23 | |
| Vitriol of Mars | iron sulfate | Ferric sulfate | Fe23 | |
| White vitriol | zinc sulfate | heptahydrate | ZnSO4·7H2O |
History
The study of vitriol began during ancient times. Sumerians had a list of types of vitriol that they classified according to the substances' color. Some of the earliest discussions of the origin and properties of vitriol is in the works of the Greek physician Dioscorides and the Roman naturalist Pliny the Elder. Galen also discussed its medical use. Metallurgical uses for vitriolic substances were recorded in the Hellenistic alchemical works of Zosimos of Panopolis, in the treatise Phisica et Mystica, and the Leyden papyrus X.Medieval Islamic chemists like Jābir ibn Ḥayyān, Abū Bakr al-Rāzī, Ibn Sina, and Muḥammad ibn Ibrāhīm al-Watwat included vitriol in their mineral classification lists.
Sulfuric acid was termed "oil of vitriol" by medieval European alchemists because it did not evaporate spontaneously in air, and it was prepared by roasting "green vitriol" in an iron retort. The first vague allusions to it appear in the works of Vincent of Beauvais, in the Compositum de Compositis ascribed to Saint Albertus Magnus, and in pseudo-Geber's Summa perfectionis.
Systematic attempts to identify and analyze the nature of the various substances classed as vitriols were in full swing by the late 17th Century.