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Liver of sulfur is a loosely defined mixture of
potassium sulfide Potassium sulfide is an inorganic compound with the formula K2 S. The colourless solid is rarely encountered, because it reacts readily with water, a reaction that affords potassium hydrosulfide (KSH) and potassium hydroxide (KOH). Most commonl ...
, potassium
polysulfide Polysulfides are a class of chemical compounds containing chains of sulfur atoms. There are two main classes of polysulfides: inorganic and organic. Among the inorganic polysulfides, there are ones which contain anions, which have the general formu ...
, potassium thiosulfate, and likely potassium bisulfide. Synonyms include hepar sulfuris, sulfur, sulfurated potash and sulfurated potassa. There are two distinct varieties: "potassic liver of sulfur" and "ammoniacal liver of sulfur".


Overview

Liver of sulfur is mainly used in
metalworking Metalworking is the process of shaping and reshaping metals to create useful objects, parts, assemblies, and large scale structures. As a term it covers a wide and diverse range of processes, skills, and tools for producing objects on every scale ...
to form a brown or black
patina Patina ( or ) is a thin layer that variously forms on the surface of copper, brass, bronze and similar metals and metal alloys ( tarnish produced by oxidation or other chemical processes) or certain stones and wooden furniture (sheen produce ...
on
copper Copper is a chemical element with the symbol Cu (from la, cuprum) and atomic number 29. It is a soft, malleable, and ductile metal with very high thermal and electrical conductivity. A freshly exposed surface of pure copper has a pink ...
and
silver Silver is a chemical element with the symbol Ag (from the Latin ', derived from the Proto-Indo-European ''h₂erǵ'': "shiny" or "white") and atomic number 47. A soft, white, lustrous transition metal, it exhibits the highest electrical ...
as well as many (though not all)
copper alloy Copper alloys are metal alloys that have copper as their principal component. They have high resistance against corrosion. The best known traditional types are bronze, where tin is a significant addition, and brass, using zinc instead. Both of t ...
s and silver alloys (
brass Brass is an alloy of copper (Cu) and zinc (Zn), in proportions which can be varied to achieve different mechanical, electrical, and chemical properties. It is a substitutional alloy: atoms of the two constituents may replace each other wi ...
, for example— a copper alloy— does not react with sulfur compounds). It is sold as a yellow brittle solid (a "lump" which must be mixed with water before use) as well as a pre-mixed liquid and a gel form. The solid is believed to have the longest shelf life, though all liver of sulfur tends to decompose with time. Modern gel forms contain stabilizers that allow the reactivity to last much longer. Liver of sulfur that is kept dry, sealed from air, out of the light, and in a freezer will last many times longer than that kept in any other condition. The highest quality liver of sulfur in solid form is a dark yellow, almost "liver" colored substance. As it ages and is exposed to air, its potency decreases, it will turn lighter yellow and finally white, at which point its reactivity is negligible. Liver of sulfur decomposes to
sulfate of potash Potassium sulfate (US) or potassium sulphate (UK), also called sulphate of potash (SOP), arcanite, or archaically potash of sulfur, is the inorganic compound with formula K2SO4, a white water-soluble solid. It is commonly used in fertilizers, prov ...
and
carbonate of potash Potassium carbonate is the inorganic compound with the formula K2 CO3. It is a white salt, which is soluble in water. It is deliquescent, often appearing as a damp or wet solid. Potassium carbonate is mainly used in the production of soap and gl ...
, neither of which has any value as an oxidizer of metal. The reactivity of liver of sulfur with silver and copper quickly creates a dark or colored patina on the metal. This is done by immersing the metal object in a solution of liver of sulfur and water. When treating silver, the solution must be hot, though If the bath is brought to its boiling point the liver of sulfur will quickly decompose and become ineffective. Also, if the concentration of the solution is too strong, the oxidation process will proceed too quickly and the layer of patina thus created will tend to flake away. The best results are usually obtained by using more dilute solutions and allowing the patina to build more slowly but more securely, and, for silver, keeping the solution just under its boiling point. Lastly, it is critical that the metal surface be extremely clean, as clean as would be necessary to electroplate the same surface. Even small amounts of oil on the metal such as that produced by handling without gloves will be sufficient to protect the metal surface from oxidation.


Medical use

Liver of sulfur was once used to counteract poisoning with several metals, including
arsenic Arsenic is a chemical element with the symbol As and atomic number 33. Arsenic occurs in many minerals, usually in combination with sulfur and metals, but also as a pure elemental crystal. Arsenic is a metalloid. It has various allotropes, b ...
, copper, lead, and
antimony Antimony is a chemical element with the symbol Sb (from la, stibium) and atomic number 51. A lustrous gray metalloid, it is found in nature mainly as the sulfide mineral stibnite (Sb2S3). Antimony compounds have been known since ancient ti ...
. A lump was dissolved in warm water and the patient was instructed to drink the solution three or four times over the course of an hour. At one time sulfurated potash was used to combat
arthritis Arthritis is a term often used to mean any disorder that affects joints. Symptoms generally include joint pain and stiffness. Other symptoms may include redness, warmth, swelling, and decreased range of motion of the affected joints. In som ...
. It eventually fell into disfavor for medical purposes because
sulfide Sulfide (British English also sulphide) is an inorganic anion of sulfur with the chemical formula S2− or a compound containing one or more S2− ions. Solutions of sulfide salts are corrosive. ''Sulfide'' also refers to chemical compounds la ...
s and
polysulfide Polysulfides are a class of chemical compounds containing chains of sulfur atoms. There are two main classes of polysulfides: inorganic and organic. Among the inorganic polysulfides, there are ones which contain anions, which have the general formu ...
s were discovered to be toxic in their own right.


References

{{DEFAULTSORT:Liver Of Sulfur Chemical mixtures