Vitriol

Vitriol is the general chemical name encompassing a class of chemical compounds comprising sulfates of certain metals – originally, iron or copper. Those mineral substances were distinguished by their color, such as green vitriol for hydrated iron(II) sulfate and blue vitriol for hydrated copper(II) sulfate.^[1]

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 dry distillation (pyrolysis) 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
Black vitriol		Sulfate • Heptahydrate ( Hydrated Sulfate)^[A]	[Cu,Mg,Fe,Mn,Co,Ni]SO₄·7H₂O^[B]
Blue vitriol/Vitriol of Cyprus/Roman vitriol^[2]	copper(II) sulfate	pentahydrate	CuSO₄·5H₂O
Green vitriol/Copperas	iron(II) sulfate	heptahydrate	FeSO₄·7H₂O
Oil of vitriol/Spirit of vitriol	sulfuric acid	acid	H₂SO₄
Red vitriol	cobalt(II) sulfate	heptahydrate	CoSO₄·7H₂O
Sweet oil of vitriol	diethyl ether	Not a sulfate, but can be synthesized from sulfuric acid and ethanol^[3]	CH₃-CH₂-O-CH₂-CH₃
Vitriol of argile/Vitriol of clay	aluminium sulfate	alum	Al₂(SO₄)₃
Vitriol of Mars	iron(III) sulfate	Ferric sulfate	Fe₂(SO₄)₃
White vitriol	zinc sulfate	heptahydrate	ZnSO₄·7H₂O

^A Many websites state that black vitriol "is a mixture of iron sulfate and iron sulfite", but none give a reference of any sort. The book, Chemistry, Inorganic & Organic, with Experiments, by Bloxam^[4] is a published, reliable reference for the composition of black vitriol, and it states on page 513, "The formula of black vitriol may be written [CuMgFeMnCoNi]SO₄·7H₂O, the six isomorphous metals being interchangeable without altering the general character of the salt."

^B "Any combination of these elements may be found in black vitriol."^[4]

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 (first century AD) and the Roman naturalist Pliny the Elder (23–79 AD). 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.^[5]

Medieval Islamic chemists like Jābir ibn Ḥayyān (died c. 806–816 AD, known in Latin as Geber), Abū Bakr al-Rāzī (865–925 AD, known in Latin as Rhazes), Ibn Sina (980–1037 AD, known in Latin as Avicenna), and Muḥammad ibn Ibrāhīm al-Watwat (1234–1318 AD) included vitriol in their mineral classification lists.^[6]

Sulfuric acid was termed "oil of vitriol" by medieval European alchemists because it was prepared by roasting "green vitriol" (iron(II) sulfate) 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 (all thirteenth century AD).^[7]

References

^ "Vitriol" entry in the online Encyclopaedia Britannica. Accessed on 2020-08-28.
^ Roman vitriol on Chembk CAS Database
^ "Synthesis of Ethers".
^ ^a ^b Bloxam, Charles Loudon; Bloxam, Arthur G.; Lewis, S. Judd (1913). "Copper, Cu = 63.57". Chemistry, Inorganic & Organic, with Experiments (Tenth ed.). Philadelphia: P. Blakiston's Son & Co. p. 513. The formula of black vitriol may be written [CuMgFeMnCoNi]SO₄·7H₂O, the six isomorphous metals being interchangeable without altering the general character of the salt.
^ Karpenko, Vladimír; Norris, John A. (2002). "Vitriol in the History of Chemistry". Chemické listy. 96 (12): 997–1005.
^ Karpenko & Norris 2002, pp. 999–1000.
^ Karpenko & Norris 2002, pp. 1002–1004.

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[ebrit.vitriol-1] "Vitriol" entry in the online Encyclopaedia Britannica. Accessed on 2020-08-28.

[2] Roman vitriol on Chembk CAS Database

[3] "Synthesis of Ethers".

[bloxam-4] Bloxam, Charles Loudon; Bloxam, Arthur G.; Lewis, S. Judd (1913). "Copper, Cu = 63.57". Chemistry, Inorganic & Organic, with Experiments (Tenth ed.). Philadelphia: P. Blakiston's Son & Co. p. 513. The formula of black vitriol may be written [CuMgFeMnCoNi]SO₄·7H₂O, the six isomorphous metals being interchangeable without altering the general character of the salt.

[5] Karpenko, Vladimír; Norris, John A. (2002). "Vitriol in the History of Chemistry". Chemické listy. 96 (12): 997–1005.

[6] Karpenko & Norris 2002, pp. 999–1000.

[7] Karpenko & Norris 2002, pp. 1002–1004.

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