An Alchemists Glossary of Terms, Definitions, Formulas & Concoctions

Iceland Spar (Calcite): A particular crystal form of Calcium Carbonate (CaCO₃).
Icy Butter: Antimony Chloride (SbCl₃).
Igneous Fluid: a postulated Elastic Fluid sometimes used synonymously with Caloric (matter of heat), sometimes with Phlogiston (matter of fire), and sometimes as a substance with the postulated properties of both.
Illinium: Another name proposed for promethium, element 61.
Imbibition: To soak or saturate with a liquid.
Infernal Stone: An Alkali Hydroxide (NaOH, KOH). [Not to be confused with the French term pierre infernale.]
Inflammable Air: Usually Hydrogen (H₂), though the usage is not constant among Priestley, Watt, Lavoisier, or Berthollet. Sometimes Carbon Monoxide (CO).
Inflammable Air from Metals: Hydrogen (H₂).
Infusion: The extraction of chemical substances by soaking them in a solvent, usually water. Sometimes boiling water was poured on a mixture of substances and then allowed to cool in order to aid the extraction; but if the heat were used, the temperature could not exceed that of boiling water.
Insolation: Digestion in which the heat was supplied by the sun rather than a furnace.
Inspissate: To thicken or condense.
Intermediate Salt of the Ley of Blood: Potassium Ferrocyanide (K₄Fe(CH)₆).
Intermediate Salts: Usually normal salts; occasionally acid salts.
Intermedium: Any reagent or reactant believed to be necessary for a reaction but which does not always appear on the product.
Intumescence: The process of swelling up.
Ionium: An isotope of thorium produced in uranium decay, namely ²³⁰Th (half-life = 80 kyr). See Table of Isotopes.
Ipecacuanha: A preparation from the root of the South American plant Cephaelis Ipecacuanha.
Iron Ochre: A mixture of silica, clay, and various Oxides of Iron. In red ochre the Oxide is simple Fe₂O₃; in yellow ochre it is Fe₂O₃^.H₂O.
Iron Vitriol: Ferrous Sulphate (FeSO₄).
Isinglass: In the first half of the 18th. century a gelatinous substance extracted from the air-bladders of certain fish. Later, a synonym for sheet mica.
Ivory-Black: A black pigment prepared by the calcination of ivory in a closed vessel.

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Jalap: A powder from the dried roots of the Mexican plant Exogonium purga. Used as a purgative.
James' Powder: A powder prepared by Dr. Robert James (1703-1776) that was used to reduce fevers.
Japanning: The coating of an object with a very dark varnish. The original varnish came from Japan, but substitutes were later found.
Jeweler's Etchant: 3g. Silver Nitrate + 3g. Nitric Acid + 3g. Mercurous Nitrate + 100cc water.
Jove (of Jove): Tin, or some compound or alloy of Tin.
Jupiter: In astrological and alchemical thought, the seven heavenly bodies known to the ancients were associated with Seven Metals also known in antiquity. Jupiter was associated with Tin. [Helmont].

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Kali: The plant Salsola kali or glasswort from which, oddly enough, "mineral" alkali (Sodium Carbonate) was extracted by calcination. Also sometimes used for crude Sodium Carbonate.
Kalium: Latin (and German) for Potassium, hence the symbol K.
Kaolin: A fine, white clay used in the manufacture of porcelain.
Kelp: Impure Soda (Na₂CO₃) from seaweed. In Britain, the term was sometimes used for crude Sodium Carbonate from any source. Also ashes of seaweed from which Carbonates or Iodine were extracted.
Kelvin Scale: An Absolute Temperature Scale (i.e., one in which absolute zero is assigned the value zero) named after William Thomson, first (and last) Baron Kelvin of Largs, who first proposed an absolute temperature scale. One Kelvin (denoted simply K or sometimes in older sources °K) is the same size as a Celsius degree, so the normal freezing point of water is 273.15 K and the normal boiling point is 373.15 K. (See Celsius Scale, Fahrenheit Scale, Rankine Scale, Réaumur Scale.) [Kelvin].
Kermes Mineral: A natural mixture of Antimony Oxide or a mixture obtained in the laboratory by the actions of Potassium Carbonate (K₂CO₃) on Antimony Sulphide.
Killed Spirits: Zinc Chloride.
King's Yellow: A mixture of orpiment with white Arsenic. Also a native yellow Arsenic (III) Sulfide, As₂S₃ (Yellow Arsenic, Yellow Orpiment).
Kurrol's Salt: A Potassium pPhosphate, (KPO₃)₄, with ion-exchange properties.

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Lac (Laque): A relatively thick solution of a colorant or coating.
Lac Sulphuris: See milk or Sulphur.
Lapis: Latin for stone; also an alchemical term for non-volatile solids.
Lapis Calaminarus (Calamine): Mineral form of Zinc Carbonate (ZnCO₃)
Lapis Causticus: Fused Sodium or Potassium Hydroxide, NaOH, KOH.
Lapis Haematites: Hematite (Fe₂O₃)
Lapis Imperialis: Silver Nitrate, AgNO₃.
Lapis Infernalis: Fixed vegetable alkali, I., Potassium Carbonate (K₂CO₃)
Lapis Lunaris: Fused Silver Nitrate, AgNO₃.
Lapis Philosophorum: A mixture of fused Alum, Vitriol, Bolus, Cerussa, Camphor, Vinegar.
Lapis Ponderous: Calcium Tungstate (CaWO₄)
Lapis Septicus: Potassium Hydroxide (KOH)
Lapis Serpentin: A mineral chiefly characterized by the presence of hydrous Magnesium Silicate (Mg₃Si₂O₅(OH)₄)
Laque: See Lac.
Laudanum: Any medicinal preparation with opium as a primary ingredient.
Laughing Gas: Nitrous Oxide, N₂O.
Lead Black: Graphite, an allotrope of Carbon.
Lead Fume: Lead Oxide obtained from the flues at lead smelters.
Lead-Glance: Lead sulphide (PbS)
Lead, Red: Lead Oxide, Pb₃O₄ (Minium, Paris Red).
Lead White: Basic Lead Carbonate, 2PbCO₃^.Pb(OH)₂ (Ceruse).
Ley of (Ox-) Blood: The lixiviate from the residue produced by igniting blood with potashes.
Ley of Soapboilers: Potassium Hydroxide (KOH)
Libavius, Fuming Liquor of (Spiritus Fumans Libavii): Tin Tetrachloride, SnCl₄, which fumes because it is hydrolyzed by moisture in the air to Stannic Oxide. First prepared at the beginning of the 17th. century by the German chemist Andreas Libavius. When mixed with one-third of its weight of water, it forms a hydrate formerly called Butter of Tin.[J. Davy].
Libra (Pound) Troy: See Apothecary Measures.
Light Carburetted Hydrogen: Marsh gas or methane (CH₄)
Light Inflammable Air: Hydrogen (H₂)
Ligne: Unit of length in late 18th. century France; see Pied. [Lavoisier].
Lignum Nephriticum: Two distinct woods were known as lignium nephriticum: (1) the small Mexican tree or shrub Eysenhardtia polystacha and the large Philippine tree Pterocarpus indica. In the 16th., 17th., and early 18th. centuries, cups, powders, and dried extracts of this wood were thought to have a great medicinal powers. The infusion was flourescent.
Lignum Vitae: "Tree of Life" The wood , and sometimes the resin, of several semitropical trees, but most often referring to Guaiacum.
Limation: Filing on a metal piece to reduce it to filings. Sometimes used for simply polishing an object.
Lime: Calcium Oxide (CaO). (Burnt Lime, Calcareous Earth, Quicklime) [Dalton, Lavoisier, Priestley, Ramsay, et al.]
Lime, Carbonate of: Calcium Carbonate (CaCO₃) (Mild Calcareous Earth, Chalk).
Lime, Chlorinated: See Bleaching Powder.
Lime, Milk of: A suspension of calcium hydroxide. See Milks.
Lime, Quick: Calcium Oxide (CaO) [Bacon, Black, Lavoisier, Priestley].
Lime, Slaked: A caustic substance Calcium Hydroxide, Ca(OH)₂, produced by heating limestone. (Hydrated Lime, Caustic Calcareous Earth).
Limestone: Calcium Carbonate (CaCO₃)
Lime Water: A solution of Calcium Carbonate (CaCO₃) Also a saturated aqueous solution of Calcium hHydroxide Ca(OH)₂ (Liquor Calcis) [Black, Dalton, Lavoisier, Ramsay et al.]
Liquescent (Salts): See Deliquescence.
Liquor Fumans Boyle (Spiritus Fumans Boyle): Ammonium Polysulphide ((NH₄)S₂; (NH₄)₂S₅).
Liquor Fumans Libavh (Fuming Liquor of Libavius): Stannic Chloride (SnCl₄).
Liquor of Flints: See Liquor Silicum.
Liquor Hoffman: A mixture of Ethanol and Ether.
Liquor of Liravius: See smoking spirit of Libavius.
Liquor Silicum (Liquor of Flints): A solution of Potassium Silicate (K₂ SiO₃). Sometimes Used for other soluble Silcates.
Litharge: Yellow Lead (II) Oxide (PbO); Reddish-Yellow crystalline form of Lead Monoxide, formed by fusing and powdering massicot. [Marignac, Priestley].
Lithomarge: Soft, claylike substances, such as kaolin.
Litmus: A blue pigment, extracted from certain lichens. It is acid sensitive, turning red in the presence of an acid. The red form turns blue again when a base is added.
Liver of Antimony: Fused Antimony Sulfide (Sb₂S₃). Usually produced from the detonation of equal parts of crude Antimony and Potassium Nitrate.
Liver of Arsenic: Fused mixture of Potassium Carbonate and (white) Arsenic. May have contained some Potassium Arsenate.
Liver of Sulphur (Hepar Sulphuris): Produced by heating Potassium Carbonate with Sulphur. Not a true compund, it is a metastable mixture of Potassium Polysulfides and Sulfate. (K₂S, K₂S₂, K₂S₃, K₂S₄, K₂S₅, K₂SO₄). Complex of Polysulphides of Potassium, made by fusing Potash and Sulphur. (melted Potassium Carbonate + Sulfur).
Livre: Unit of mass in the late 18th. century France: 1 livre (Paris pound) = 16 onces; 1 once (Paris ounce) = 8 gros; 1 gros = 72 grains. In modern units, the livre is equivalent to 489 grams or about 1.08 pounds in the "English" system still commonly used in the United States. [Proust].
Lixivial Salts: Salts prepared by lixiviations.
Lixiviate of Mars: Possibly a tincture of Iron, of which there were many different preparations. Typically, these were solutions of salts of Iron to which rectified spirit of wine (Ethanol, (CH₃CH₂OH) was added .
Lixiviation: Separation of soluble from unsoluble solid substances by soaking the mixture of solids and removing the resulting solution which contained the soluble material.
Lixivium: A solution produced by lixiviation. Sometimes used as a general synonym for "Solution"
Lixivium of Tartar: A solution of Potassium Carbonate (K₂CO₃)
Load: Any ore.
Logwood: The American tree Haematoxylon campechionum, used in dying. It produces dark shades: blacks, blues, and dark grays.
Lucillite: A variety of limestones.
Lunar Cornea: Fused Silver Chloride (AgCl). The soft colourless tough mass of Silver Chloride, made by heating Horn Silver until it forms a dark yellow liquid and then cooling. Described by Oswald Croll in 1608.
Lunar Caustic: Fused Silver Nitrate (AgNO₃). See Moon.
Lunar Crystals: Finely divided parts of Silver Nitrate (AgNO₃). In preparing these crystals great care was taken to use only the purest Silver and Nitric Acid possible.
Lunar Nitre: Silver Nitrate (AgNO₃).
Lye: Potassium Hydroxide solution, KOH.

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Mageration: The softening and weakening of a solid sample, even to the point of partial decomposition, by soaking it in a liquid.
Magisterium Tartari Vitriolati: Probably Potassium Sulfate (K₂SO₄).
Magistery of (any substance): A precipitate of any substance, i.e., a pure form of the substance which has been separated by precipitation.
Magistery of Bismuth: Basic Bismuth Nitrate (BiNO₃ ^. H₂O); sometimes the Oxide (BiO) or even the Oxychloride (BiOCl).
Magistery of Coral: Calcium Carbonate (CaCO₃).
Magistery of Sulfur: Precipitated milk of Sulphur (S).
Magistry: Any substance prepared from the basic elements of the substance without impurities. A magistry was supposed to be closer to the ideal for a substance than was usual for real chemical preparations.
Magnesia: Magnesium Carbonate (MgCO₃). [Modern Magnesia = Magnesium Oxide (MgO)]. Some chemists called Magnesium (Mg) by the name Magnesia.
Magnesia Aerata: Magnesium Carbonate (MgCO₃).
Magnesia Alba: Magnesium Carbonate (MgCO₃). Literally "white magnesia" was a hydrated Magnesium Carbonate, also known as mild Magnesian Earth. [Black, Scheele] 4MgCO₃^.Mg(OH)₂^.5H₂O was Magnesia Alba Levis, and MgCO₃^.Mg(OH)₂^.4H₂O was Magnesia Alba Ponderosa.
Magnesia Nigra: Natural Manganese Dioxide (MnO₂). Literally "Black Magnesia" was the mineral pyrolusite, sometimes also called simply Magnesia or Manganese. [Scheele] Eventually Manganese became the name of the metal present in the mineral.
Magnesia Salita: Magnesium Chloride (MgCl₂).
Magnium: Sir Humphry Davy's name for Magnesium (Mg), the metal obtained from Magnesia Alba, proposed to avoid confusion with the metal found in Magnesia Nigra.
Magnus Salt: Tetrammineplatinum Tetrachloroplatinate, Pt(NH₃)₄PtCl₄, named after Heinrich Gustav Magnus.
Malachite, Green: Pulverized Malachite, a basic Copper Carbonate mineral, (CuCO₃ ^. Cu(OH)₂), used as a pigment; or a green Triphenylmethane dye, C₂₃H₂₅N₂Cl, also known as Victoria Green or Benzal Green, an acid-base indicator that changes from yellow to blue-green as the pH is raised through 1
Malic Acid: An acid extracted from apples and various other fruits. Pure Malic Acid is C₄H₆O₅.
Malt: Barley or other suitable grains after a preparation for brewing or distilling that usually included soaking, germination, and drying.
Manganese: Manganese Dioxide (MnO₂). Manganese as we know it was called Reglus of Manganese.
Manganese, Black: See Magnesia Nigra.
Manganese, Green: Barium Manganate, BaMnO₄.
Manganese, Red: Rhodonite, MnSiO₃, a Manganese Silicate mineral, or Rhodochrosite, a Manganese Carbonate mineral, MnCO₃.
Manna Mercurii: Mercurous Chloride (Hg₂Cl₂).
Marble: A hard, crystalline, mineral form of Calcium Carbonate (CaCO₃).
Marcasita Plumbea: Antimony (Sb).
Marcasites: Minerals similar in appearance or properties to Iron Pyrites (FeS₂). Later, a general term for Pyrites. Sometimes the term was used for Sulfides of Arsenic (As₂S₂, As₂S₃, As₂S₅). Mineral form of Iron Disulphide. Oxidises in moist air to Green Vitriol.
Marchpane: See Marzipan.
Marignac Salt: Potassium Tin (II) Sulfate, K₂Sn(SO₄)₂, named for Jean de Marignac, who is best known for atomic weight measurements.
Marine Acid: Hydrochloric Acid solution (HCl). (Muriatic Acid, Spirit of Salt).
Marine Acid Air: Gaseous Hydrogen Chloride (HCl). [Cavendish, Lavoisier, Priestley, Scheele, et al.].
Marine Alkali: Sodium Carbonate (Na₂CO₃). (Common Mineral Alkali, Fossil Alkali, Soda).
Mariott's Law: Better known today as Boyle's Law, that the product of pressure and volume of a gas is constant; named for Edme Mariotte, who discovered it independently some time after Boyle. (P₁V₁ = P₂V₂)
Marl (Marle): A loose soil of clays and Calcium Carbonate (CuCO₃).
Mars (of Mars): In astrological and alchemical thought, the seven heavenly bodies known to the ancients were associated with Seven Metals also known in antiquity. Mars was associated with Iron.
Marsh Gas: Methane (CH₄).
Martial Balls: A mixture of Iron fillings (Fe) and Cream of Tartar (KHC₄H₄O₆).
Martial Ethiops: Hydrated Ferrosoferric Oxide (Fe₃O₄ ^. xH₂O).
Martial Extract: Concentrated tincture of mars. A concentrated solution, the chief component of which may have been Ferrous Hydroxide (Fe(OH)₂).
Martius Yellow: Yhe Calcium Salt of Naphthalene Yellow.
Marzipan: A confection of pounded almonds, sugar, and other ingredients.
Massicot: Yellow powder form of Lead Monoxide. PbO. Lead (II) Oxide, PbO.
Masurium, (Ma): Another name proposed for technetium, element 43.
Matrass: A vessel with a round bottom and long, slender neck. Used as part of several common types of distillation apparatus.
Menstruum: A solvent.
Mephitic (as adjective): Noxious; poisonous or pestilential.
Mephitic Acid: Carbonic Acid (H₂CO₃).
Mephitic Air: Carbonic Acid (CO₂).
Mercurius Calcinatus Per Se: Mercuric Oxide (HgO), prepared by the Calcination of Mercury [Priestley, Watt]. The substance known as Precipitated Mercury Per Se [Lavoisier, Priestley] or Red Precipitate [Priestley, Scheele] is the same substance; however, because of its different preparation (by mixing Mercury with Nitric Acid, evaporating, and heating the residual Mercuric Nitrate), the identity was not at first realized.
Merc. Calcin. Nitrat: Mercuric Nitrate (Hg(NO₃)₂).
Mercurius Corrosivus: Mercuric Chloride HgCl₂.
Mercuric Corrosivus Ruber: Mercuric Oxide (HgO).
Mercurius Dulcis (Calomel, Mercurious Sublimatus Dulcus, Mild Mercury): Mercurous Chloride (Hg₂Cl₂).
Mercurius Praecipitatus Per Se: Red Mercuric Oxide (HgO). Described by Geber.
Mercurius Praecipitatus Ruber: Mercuric Oxide (HgO).
Mercurius Solubilis Hahnemanni: Mercuric Oxide (Hg₂O).
Mercurius Sublimatus Dulcis (Calomel, Mercurius Dulcis, Mild Mercury): Mercurous Chloride (Hg₂Cl₂).
Mercurius Sublimatus Rubeus non Corrosivas: Mercuric Oxide (HgO).
Mercurius Vitae: Mixture of Antimony Oxychloride and Antimony Oxides (Sb₂O₃; Sb₂O₄, Sb₂O₅, SbOCl). In some contexts the term may mean just Antimony Oxychloride (SbOCl).
Mercurius Vitae Antimonii: Mixture of Antimony Oxychloride and Antimony Oxide (Sb₂O₃; Sb₂O₅, SbOCl).
Mercury: In astrological and alchemical thought, the seven heavenly bodies known to the ancients were associated with Seven Metals also known in antiquity. Mercury was associated with Mercury (Quicksilver, hydrargyrum).
Mercury of Life: See Mercurius Vitae.
Mesothorium: There were two Mesothoriums produced in Thorium decay. Mesothorium I is an isotope of Radium, namely ²²⁸Ra (half-life = 5.8 y); Mesothorium II is an isotope of Actinium, namely ²²⁸Ac (half-life = 6 hr). See Table of Isotopes.
Metallic Salt: Compound of a metal and an acid.
Metanil Yellow: The Sodium salt of 4'-Analine Azobenzenesulfonic Acid, C₁₂H₁₀N₃O₃SNa, an acid-base indicator that changes from red to yellow as the pH is raised through 1.8.
Methyl, Green: C₂₅H₃₀N₃Cl, a Triphyenylmethane dye and acid-base indicator that changes from yellow through blue-green to colorless as the pH is raised.
Methyl, Orange: Sodium p-Dimethylaminobenzenesulfonate, C₁₄H₁₄O₃N₃SNa, an acid-base indicator that changes from red to yellow as the pH is raised through 3.8.
Methyl, Red: o-Dimethylaminoazobenzenecarboxylic Acid, C₁₅H₁₅O₂N₃, an acid-base indicator that changes from yellow to reddish purple as the pH is raised through 4.5.
Methylene Blue: 3,9-Bisdimethylaminophenazothionium Chloride Trihydrate, C₁₆H₁₈N₃SCl^.3H₂O, a thiazine dye and redox indicator.
Miasma (Miasmata): A noxious or infectious subtle material (e.g., a vapor or exhalation) thought to be from decaying organic matter. Sometimes used for any unseen poisonous or infectious substance.
Mica: A mixed mineral form composed mostly of Aluminum Silicate but with silicates of other metals. Several complicated minerals are variously, and in combination, referred to as mica; e.g., biotite K(Mg, Fe)₃AlFeSi₃O₁₀(OH, F)₂.
Microcosmic Salt: An acid Sodium Ammonium Phosphate (NaNH₄HPO₄ ^. 4H₂O), found in blood and natural waters.
Mild Alkali: Alkalies which produce effervescence with acids; i.e., Carbonates (-CO₃²¯)
Mild Calcareous Earth: Calcium Carbonate (CaCO₃).
Mild Magnesian Earth: Magnesium Carbonate (MgCO₃).
Mild Mercury: Mercurous Chloride (Hg₂Cl₂).
Mild Vegetable Alkali: Potassium Carbonate (K₂CO₃).
Milk: Mineral "milks" or magmas are aqueous suspensions.
Milk of Barium: An aqueous suspension of Barium Hydroxide, Ba(OH)₂.
Milk of Bismuth: An aqueous suspension of basic Bismuth Nitrates, Bi(OH)₂NO₃ and/or BiOH(NO₃)₂.
Milk of Lime: An aqueous suspension of Calcium Hydroxide (suspension) (Ca(OH)₂). [Scheele] See Lime.
Milk of Magnesia: An aqueous suspension of Magnesium Hydroxide, Mg(OH)₂, especially a 7% suspension used as an antacid. See Magnesia.
Milk of Sulphur (lac sulphuris): Finely divided white colloidal Sulfur (S) in solution. Usually the product of the reaction between a soluble sulfide and an oxidizing acid. Geber made this by adding an acid to thion hudor.
Millon's Base: (HOHg)₂NH₂OH, formed from a solution of Mercuric Oxide in Ammonium Chloride; named for A. N. E. Millon.
Minderer's Spirit: A solution of Ammonium Acetate (NH₄C₂H₃O₂).
Mineral Alkali: Hydrated Sodium Carbonate (Na₂CO₃). (Fossil Alkali, Marine Alkali, Soda)
Mineral Anodyne of Hoffman (Liquor of Hoffman): A mixture of Ethanol and Ether (C₂H₅OH), (CH₃CH₂OCH₂CH₃).
Mineral Crystal (Sal Prunella): Potassium Nitrate with a small admixture of Potassium Sulfate (HNO₃; K₂SO₄).
Mineral, Dye: An inorganic pigment.
Mineral Blue: A blue Copper or Tungsten ore, or a mixture of Ferriferrocyanide, Fe₄[Fe(CN)₆]₃, with Calcium or Barium Sulfate, BaSO₄.
Mineral Green: Copper (II) Carbonate, CuCO₃.
Mineral Purple: A reddish Iron Oxide pigment
Mineral White: A natural hydrated Calcium Sulfate
Mineral Yellow, Cassel Yellow: Lead Oxychloride, PbCl₂^.2PbO.
Minim: See Apothecary Measures.
Minium (Red Lead, Paris Red): Scarlet crystalline powder Lead Tetroxide (Pb₃O₄). Triplumbic Tetroxide. Formed by roasting litharge in air. [Lavoisier, Priestley]. Minium once referred to Cinnabar (Mercuric Sulfide, HgS) as well, but now is used only for its cheif adulterant, red Lead Oxide.
Mixt: A chemical union of two or more true "elements" or "principles." Later, any substance which could be resolved into constituent parts only by chemical means. Although the term has greater philosophical complexities, it was roughly equivalent to our term "compound," but the latter is not to be considered a synonym.
Mixtura Salina: Saline mixture prepared by saturating Potassium Carbonate with lemon juice and adding syrup of black currants, julep.
Mofette: An exhalation or vapor of a mephitic (noxious or poisonous) gas.
Mohr's Salt: Ferrous Ammonium Sulfate (FeSO₄((NH₄)₂SO₄ ^. 6H₂O), named for Karl Friedrich Mohr.
Molecule: Does not necessarily correspond to the modern conception of two or more atoms chemically bound together. Avogadro, for example, meant something like "ultimate particle of a substance"; his elementary molecule corresponds to a modern atom and his composite molecule to a modern molecule. (See Atom.).
Molybdaena: Native Molybdenum Sulfide (MoS₂).
Monsel Salt: An Iron Sub-Sulfate, Fe₄(SO₄)₅O.
Monthier Blue: A blue pigment, FeNH₄[Fe(CN)₆].
Moon (Luna): In astrological and alchemical thought, the seven heavenly bodies known to the ancients were associated with Seven Metals also known in antiquity. The moon was associated with Silver (argentum). See Lapis Lunaris, Lunar Caustic.
Mordant: Any substance which fixes or holds a colorant in the material to be dyed.
Mortify: To change or destroy the normal, external form or appearance of a substance.
Mosaic Gold: Golden-yellow glistening scales of crystalline Stannic Sulfide (SnS₂), made by heating a mixture of Tin filings, Sulphur and Sal Ammoniac. Tin (IV) Sulfide, SnS₂, a pigment.
Mucilagenous Matter: Any semisolid material that was soft, moist, and viscous.
Mundic (Mundick): Iron Pyrites (FeS₂). Sometimes used for other pyrites or as a general term for pyrites.
Muriates: Chlorides (-Cl¯); see Muriatic Acid. [Avogadro, Gay-Lussac, Thenard, T. Thomson]
Muriate of Mercury: Mercuric Chloride.
Muriatic Acid (Acidum Salis): Hydrochloric Acid (HCl) ( Marine Acid, Spirit of Salt); Muriatic Gas is gaseous HCl. [Black, Gay-Lussac, Prout, Scheele, Thenard, et al.]
Muriatic Ether: Probably impure Ethyl Chloride (CH₃CH₂Cl).
Mustard Gas: Di(chloroethyl)sulfide, (ClCH₂CH₂)₂S, used as a chemical weapon in World War I.

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Naples Yellow or Cassel Yellow: Lead Antimoniate (Pb₃(SbO₄)₂). Also: An Oxychloride of Lead, made by heating litharge with Sal Ammoniac.
Naptha: Any highly inflammable, volatile, naturally occurring mixture of hydrocarbons. Also could be obtained as the "lightest" fraction in the distillation of asphalts, bitumens, and petroleum.
Napthalene Yellow: Dinitro-1-naphthol, C₁₀H₅(NO₂)₂OH.
Naples Yellow: Lead Antimoniate, Pb₃(SbO₄)₂, used as a yellow pigment.
Natrium: Latin for Sodium, hence the symbol Na.
Natron (Natrum): Sodium Sesquicarbonate, a naturally occurring combination of Sodium Carbonate (Na₂CO₃) and Sodium Bicarbonate (NaHCO₃) in the ratio 1:1 (Na₂CO₃ ^. NaHCO₃ ^. 2H₂O).
Neutral Arsenical Salt of Macquer: Potassium Dihydrogen Arsenate (KH₂AsO₄).
Neutral Red: Dimethyldiaminotoluphenazine Hydrochloride, also known as Toluylene Red; an acid-base indicator that changes from blue to magenta as the pH is raised through 7.5 and then to orange-yellow as pH is raised through 8.
Neutral Salts: Salts resulting from the reaction of an acid and a base (hydroxide) but having no characteristics of either acid or base.
Nickel: Named by the copper miners of Westphalia the 'kupfer-nickel' or false copper.
Nihil Album (sometimes just Nihil): Flowers of Zinc, Zinc Oxide (ZnO).
Nile Blue: C₂₀H₁₉ON₃, an analine dye and acid-base indicator that changes from yellow through blue to magenta as the pH is raised.
Niton: The element Radon, Rn, or one of its isotopes, ²²²Rn (half life = 3.8 d). See Emanation and Table of Isotopes.
Nitrated Earths, Metals, etc.: Nitrates (-NO₃).
Nitre (Common Nitre or Niter): Potassium Nitrate (KNO₃). (Saltpeter). Black gunpowder was made from Nitre, Charcoal, and Sulfur. [Cavendish, Mayow, Priestley, Rayleigh, Watt, et al.].
Nitre, Chile: Sodium Nitrate, NaNO₃.
Nitre, Mercurial: Mercuric Nitrate, Hg(NO₃)₂ [Scheele].
Nitre, Norwegian: Calcium Nitrate, Ca(NO₃)₂.
Nitre, Rough: Magnesium Chloride, MgCl₂.
Nitre, Spirt of: See Spirit.
Nitre Fixed by Tartar: A mixture of nitre and tartar left after reaction between the two.
Nitre with an earthy base: Usually Calcium Nitrate (Ca(NO₃)₂).
Nitreum (Bergman): Nitrous Acid (HNO₂).
Nitric Acid: Nitric Acid HNO₃, formerly referred to Nitrogen Dioxide, NO₂ [Avogadro, Dalton, Gay-Lussac, Lavoisier et al.] or Nitrogen Pentoxide, N₂O₅ [Prout].
Nitro-Aerial Spirit: The hypothetical subtle substance which was though by some to be responsible for the ability to nitre to support combustion and to be a key component of detonations
Nitrous Acid: Nitrous Acid (HNO₂), formerly referred to Nitric Acid, HNO₃ (Aqua Fortis, Spirit of Nitre) [Lavoisier], or Nitrous Acid, HNO₂, or a mixture of these acids; or one or more of the Nitrogen Oxides N₂O₃, NO₂, N₂O₄, N₂O₅ [Avogadro, Dalton].
Nitrous Acid Vapor (Priestly): Nitrogen Dioxide (NO₂).
Nitrous Air (Priestly): Nitric Oxide (NO)
Nitrous Ether: Ethyl Nitrite (CH₃CH₂NO₂).
Nitrous Gas (Lavoisier): Specifically Nitric Oxide (NO) (Nitrous Air) [Avogadro, Dalton, Gay-Lussac, T. Thomson, et al.]; or a mixture of Nitrogen Oxides such as that produced by the action of Nitric Acid on a metal in the presence of air
Nitrum Aegypticum: Sodium Carbonate (Na₂CO₃).
Nitrum Antimoniatum: Product containg Potassium Nitrate, Nitrite, and Antimonate.
Nitrum Commun: See commom Nitre
Nitrum Cubic: See Cubic Nitre
Nitrum Fixatum (Nitrum Fixum, Fixed Nitre): An ofter impure preparation of Potassium Carbonate (K₂CO₃).
Nitrum Flammans: Ammonium Nitrate (NH₄NO₃). Made by Glauber.
Nitrum Regeneratum: Potassium Nitrate (KNO₃).
Nitrum Saturni: Lead Nitrate (Pb(NO₃)₂).
Nitrum Stibnatum: Probably Anitmony Nitrate (2Sb₂O₃^.N₂0₅).
Nitrum Sulphure Purgatum: Mixture of Potassium Nitrate (KNO₃) and Potassium Sulfate (K₂SO₄).
Nitrum Vitriolatum: Mixture of Potassium Nitrate (KNO₃) and Potassium Bisulfate (KHSO₄).
Non Metals: A term used by William Cullen and his students for the following group of substances; Zinc (Zn), Anitmony (Sb), Bismuth (Bi). Arsenic (As), Platinum (Pt), Cobalt (Co), Nickel (Ni).
Nordhausen Acid (Oleum): Fuming Sulfuric Acid. (H₂SO₄), i.e. a solution of Sulfur Trioxide, SO₃, in concentrated (about 98%) Sulfuric Acid.

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Ochre (Ocher): A class of mineral solids which, in powdered form, were commonly used as pigments. Their colors varied from yellow to brown, including reddish hues. Chemically, the ocheres are Iron Oxides, or mixtures of Iron Oxides, in varying states of hydration. For example red ochre is primarily Fe₂O₃. Silicates, Carbonates, Sulfates, etc. also were commonly present with these Oxides.
Ochre, Antimony: Stibiconite, an Antimony mineral, Sb₂O₃(OH)₂.
Ochre, Bismuth: Bismite, Bi₂O₃^.3H₂O.
Ochre, Brown: Bogore or Bog Iron Ore, 2Fe₂O₃^.3H₂O.
Ochre, Molybdic: Molybdite, yellow Molybdenum (VI) Oxide, MoO₃.
Ochre, Nickel (Nickel Bloom): Annabergite, Ni₃As₂O₂^.8H₂O, a green mineral.
Ochre, Plumbic: Brown Lead (IV) Oxide, PbO₂.
Ochre, Red: Hematite, Fe₂O₃.
Ochre, Telluric: Yellow Tellurium (IV) Oxide, TeO₂.
Ochre, Tungstic: Yellow Tungsten (VI) Oxide, WO₃.
Ochre, Yellow: A mixture of powdered Iron Oxide and clay.
Ochroite: Cerium Oxide (CeO₂).
Offa Helmonth: Potassium Carbonate (K₂CO₃).
Oil: Any relatively insoluble, inflammable, somewhat viscous liquid.
Oil Gas: Mixture of Methane, Carbon Monoxide, and Butlylene (CH₄, CO, C₄H₈).
Oil of Ants: Furfural, C₅H₄O₂.
Oil of Apples: n-Pentyl Pentanoate, C₅H₉CO2C₅H₁₁ (amyl valerate). Today it belongs to a group known as Esters.
Oil of Arsenic: Arsenic Trichloride (AsCl₃)
Oil of Banana (Oil of Pear): n-Pentyl Acetate, CH₃CO₂C₅H₁₁.
Oil of Chalk: Calcium Chloride solution (CaCl₂).
Oil of Cloves: An oily substance extracted from the buds and flower stalks of the clove tree Caryophyllus aromaticus. Used as medicinal.
Oil of Cognac (Enanthic Ether): Ethyl Hexyl Ether, C₆H₁₃OC₂H₅.
Oil of Dippel: The insoluble, viscous fraction from decomposed animal matter that has gone through repeated distillations.
Oil of Garlic: Allyl Sulfide, (C₃H₅)₂S
Oil of Glonoin: Nitrogylcerin, C₃H₅N₃O₉.
Oil of Hartshorn: A crude animal oil obtained from the destructive distillation of bones
Oil of Lime: A solution of Calcium Chloride (CaCl₂).
Oil of Mars: Deliquescent Anydrous Ferric Chloride.
Oil of Mirbane: Nitrobenzene, C₆H₅NO₂.
Oil of Mustard: Allyl Isothiocyanate, C₃H₅NCS.
Oil of Pear (Oil of Banana): n-Pentyl Acetate, CH₃CO₂C₅H₁₁.
Oil of Pineapple: Ethyl Butyrate, C₃H₇COOC₂H₅.
Oil of Rue: The oil extracted from evergreens of the genus Ruta. Used as Medicinal
Oil Sulphur: Concentrated sulfuric acid. Sometimes the term was used for Alkaline Sulphide of Ammonia (NH₄)₂S).
Oil of Tartar: Concentrated Potassium Carbonate solution (K₂CO₃).
Oil of Tartar per Deliquium: Potassuim Carbonate, which is hydroscopic, dissolved in the water which its extracts from the air.
Oil of Venus: Concentrated solution of Copper Nitrate (Cu(NO₃)₂.
Oil of Vitriol (Oil of Sulfur, Per Campanum): Sulfuric Acid (H₂SO₄). Made by distilling Green Vitriol. Vitriolic Acid
Oil of Wine: A hypothetical component of Alcohol thought to give it its odor and inflammability
Olea Terebinthine: Terpentine
Olefiant Gas: Ethylene (C₂H₂). Also referenced as Ethene, C₂H₄ [Dalton, Prout, Thenard, T. Thomson, et al.]. See Dutch Oil.
Oleum: Latin for oil. Also, fuming Sulfuric Acid (Nordhausen Acid).
Oleum Dulce: See Oil of Wine
Oleum Suphuris per Campanum: Sufuric Acid (H₂SO₄) prepared by burning Sulfur under a bell jar and later concentrating and purifying the product by heating to drive off water and sulfur dioxide.
Oleum Succini: Concentrated Succinic Acid( HOOCCH₂CH₂COOH).
Oleum Tartar per Demiquium: See Oil of Tartar per Deliquium
Oleum Vitriol: Oil of Vitriol
Orpiment, Red (Realgar, Red Arsenic): Arsenic (II) Sulfide, As₂S_2.
Orpiment, Yellow (Auri-Pigmentum, Yellow Arsenic, King's Yellow): Yellow ore of Arsenic. Arsenic Trisulfide (As₂S₃), Arsenic (III) Sulfide, As₂S₃.
Ounce: Unit of mass in late 18th. century France; see Livre. [Lavoisier].
Oxycarburetted Hydrogen: Water gas mixture or Hydrogen (H₂), Carbon Monoxide, (CO), and Carbon Dioxide (CO₂).
Oxymuriatic Acid (Oxygenated Muriatic Acid): Chlorine (Cl₂). (Dephlogisticated Marine Acid); named on the belief that it was a compound of Oxygen and HCl (Muriatic Acid). [Avogadro, Berzelius, Davy, Thenard]

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Panacea: Potassium Sulfate (K₂SO₄).
Pan-Stone: Calcium Sulfate (CuSO₄).
Paris Blue: Ferric Ferrocyanide, Fe₄[Fe(CN)₆]₃.
Paris Green: Copper (II) Acetoarsenite, Cu(C₂H₃O₂)₂^.3Cu(AsO₂)₂.
Paris, Plaster of: Hemihydrated Calcium Sulfate, 2CaSO₄^.H₂O.
Paris Red: Colcothar or Minium
Paris Yellow (Leipzig Yellow): Chrome Yellow.
Parting: The operation by which Gold and Silver are separated from each other.
Patent Yellow: Lead Oxychloride, PbO^.PbCl₂.
Pearl Ash: The whitest impure calcined Potassium Carbonate (K₂CO₃) extracted from calcined plants. In a sense pearl ash is purified potash.
Pearl White: Basic Nitrate of Bismuth, Bismuth Oxychloride [BiOCl], used by Lemery as a cosmetic.
Pelican: A special distillation apparatus. The condensing head had two curved tubes emerging on opposite sides. These tubes led down and entered the lower section or body of the vessel; thus, the condensed liquid ran back to the heated section where it was revaporized, giving a cyclic action. The pelican was especially effective for reactions that took place in the vapor phase.
Péligot's Salt: Potassium Chlorochromate, KCrO₃Cl, named for Eugène Péligot.
Pellicle: Any thin saline crust that forms on a solution.
Per Campanum: Any process carried out under a solution.
Per Deliquium: A hygroscopic salt was said to "run per deliquium" when it changed from solid to liquid by extracting water from the air.
Perkin's Mauve (Violet): See Aniline Purple.
Perlate Salt: Sodim Phosphate (Na₃PO₄).
Perspiration: Spontaneous evaporation or (less often) vaporization through heating. Also used to indicate condensation of moisture on a relatively cool body.
Perspirative: A medcinal which promoted perspiration.
Petrolia: Liquid bitumens.
Petunise: A white mineral solid used in the manufacture of porcelain.
Pewter: An alloy of Tin. Originally with up to one-fifth Lead, but later Bismuth and Copper were substituted for lead.
Phenol Red: Phenolsulfonphthalein, C₁₉H₁₄O₅S, an acid-base indicator that changes from yellow to red as the pH passes through 8.
Philosopher's Wool or nix alba (white snow): Zinc Oxide (ZnO). Made by burning Zinc in air. Called Zinc White and used as a pigment.
Philosophical Flowers of Vitriol: Boric Acid (H₃BO₃).
Philosophical Foliated Earth: Potassium Acetate (KC₂H₃O₂).
Philosophical Mercury: An alchemical term signifying the property-bearing principle of chemical activity.
Philosophical Sal Ammoniac: Ammonium Sulfate ((NH₄)₂SO₄).
Philosphical Spirit of Nitre: Nitric Acid prepared by distilling saltpeter with Oil of Vitriol (HNO₃).
Philosophical Spirit of Tartar: Potassium Hydrogen Tartrate (KHC₄H₄O₆) distilled with wine.
Philosophical Spirit of Vitriol: Hydrochloric Acid (HCl).
Philosophical Spirit of Wine.: Spirit of wine (Alcohol) concentrated by freezing (CH₂CH₃OH).
Philosophical Water (Aqua Regia): A solution of Hydrochloric and Nitric Acids, usually in ratios from 2:1 to 4:1 (HCl to HNO₃).
Phlegm: A general term for any aqueous fraction of a distillation.
Phlogisticated Acid of Nitre: Nitrous Acid (HNO₂).
Phlogisticated Acid of Vitriol: Sulphurous Acid (H₂SO₃).
Phlogisticated Air: Nitrogen (N₂).
Phlogisticated Alkali: Potassium Ferrocyanide (K₄Fe(CN)₆ ^. 3H₂O).
Phlogisticated Calx of Iron: Ferrous Oxide (FeO).
Phlogisticated Earth of Molybdaena: The solid reduction of Molybdic Acid.
Phlogisticated Manganese: Manganous Carbonate (MnCO₃).
Phlogisticated Nitre: Impure Potassium Nitrite (KNO₂).
Phlogisticated Nitrous Acid: Nitrous Acid (HNO₂).
Phlogisticated Vitriolic Acid: Sulfurous Acid (H₂SO₃).
Phlogiston: A hypothetical substance originally used to account for the property of inflammability. It later was made to carry many more properties and formed a central point for the theoretical beliefs of a central point for the theoretical beliefs of a number of 18th. century chemists. Also referenced as a hypothetical Elastic Fluid which was seen as a metalizing and combustible principle. Metals were seen as the result of combining calces with phlogiston; smelting expelled the phlogiston. In combustion, phlogiston leaves the combustible body to combine with air or saturate air. The theory of phlogiston is associated with Stahl. [Cavendish, Priestley, Scheele, Watt et al.]
Phlogiston Elasticum: Hydrogen (H₂).
Phosphorated Iron: Ferric Phosphate (FePO₄).
Phosphorated Mercury: Mercuric Phosphate (Hg₃(PO₄)₂).
Phosphorated Vegetable Alkali: Potassium Phosphate (K₃PO₄).
Phosphorous: Sometimes used for any phosphorescent substance.
Phosphorous of Baldwin: Calcium Nitrate (Ca(NO₃)₂).
Phosphorous of Homberg: Calcium Chloride (CaCl₂).
Phosphorous of Urine: As the name implies, a form of Phosphorous (P) extracted from urine.
Phosphuretted Hydrogen: phosphine, PH₃ [Dalton].
Pied: A Unit of length in late 18th. century France: 1 pied (Paris foot) = 12 pouces; 1 pouce (Paris inch) = 12 lignes. In modern units, the pied is equivalent to 0.325 meters or about 1.07 feet in the "English" system still commonly used in the United States. [Lavoisier].
Pierre Infernale: Fused Silver Nitrate, AgNO₃.[Not to be confused with "Infernal Stone."]
Pinch Beck: A gold colored alloy of about five parts Cooper (Cu) to one part Zinc (Zn).
Pinguious (Pinguinous): Fatty, oily
Pinte: A volume unit in late 18th. century France, equal to 2.01508 English pints, 58.145 cubic inches, or 0.953 liters. [Lavoisier]
Plaster: Any semisolid plastic mixture that could be applied to a a surface and then spontaneously cured or hardened. One of the oldest plasters is a mixture of Slaked Lime (Ca(OH)₂), sand, and hair. The term also was used to refer to impure Lead Oleate (Pb(C₁₈H₃₃O₂)₂).
Plaster of Paris: Calcium Sulfate Monohydrate ((CaSO₄)₂ ^. H₂O).
Platina: Platinum (Pt.), or sometimes the usually impure form of Platinum found in nature that is alloyed with other exotic metals.
Plessy's Green (Arnaudon's Green): Chromium (III) Phosphate, CrPO₄, a green pigment.
Plimmer's Salt: Sodium Antimony Tartrate, Na(SbO)C₄H₄O₆.
Plumbago: A lead ore, including Lead Oxide (Litharge) or Lead Sulfide (Galena); or Graphite an allotrope of Carbon (C) (Black Lead). [Lavoisier, Priestley, Thenard]
Plumbum: Latin for lead, hence the symbol Pb.
Plumbum Album: Basic Lead Carbonate (2PbCO₃ ^. Pb(OH)₂). Sometimes the term was applied to basic Lead Acetate (Pb(C₂H₃O₂) ^. Pb(OH)₂ ^. H₂O).
Plumbum Cinereum: Bismuth (Bi).
Plumbum Corneum (Horn Lead): Lead Chloride (PbCl₂).
Plumbum Stridens: Tin (Sn)
Pneumatic: Pertaining to subtle, rarified, or vaporous substances such as air. In modern terms, gaseous.
Pneumatic Trough: An apparatus developed over the 18th. century from John Mayow (1641-1679) through Stephen Hales (1677-1761) to Antoine Lavoisier (1743-1794). The trough was any large pan or vat in which inverted bottles full of water could be supported. Glass tubes conducted the gases from the vessels in which they were generated outside the trough to the inverted bottle in the trough, where the gases were trapped and held.
Point of Saturation: The instant when the exact proportions of the two "saline principles" ( one from an acid, the other from a base) unite to form a perfectly neutral salt.
Pomphlix: Flowers of Zinc (ZnO).
Pompholix: Crude Zinc Oxide, ZnO (Flowers of Zinc). [Lavoisier].
Ponderous Spar: Barium Sulfate (BaSO₄).
Pot Ash (Potash): Crude or purified Potassium Carbonate (K₂CO₃). (Vegetable Alkali, Pearl Ash) or crude Sodium Carbonate Na₂CO₃ leached from the ashes of plant material; or Potassium Hydroxide, KOH (Lye), or even Potassium Oxide, K₂O. [Dalton, Rayleigh, T. Thomson et al.]
Pouce: Unit of length in late 18th. century France; See Pied.
Powder of Algaroth: A white powder of Antimonious Oxychloride (SbOCl), made by precipitation when a solution of Butter of Antimony in spirit of salt is poured into water.
Praecipitate Per Se: Mercuric Oxide (HgO).
Praecipitatus Albus: Mercurous Chloride (Hg₂Cl₂).
Praecipitatus Vigonis: Mercuric Oxide (HgO).
Precipitant: A substance serving as intermediary to separate two other substances from each other.
Precipitate, Black: Hg₂O^.Hg₂NH₂NO₃, also known as Hahnemann's mercury, a black powder used as an antisyphilitic.
Precipitate, Red: See Mercurius Calcinatus Per Se.
Precipitate, White (Sal Sapientiae, Sal Alembroth: HgNH₂Cl; an insoluble white powder used in medicine as an antiparasitic.
Precipitate, Yellow: Yellow Mercury (II) Oxide, HgO.
Precipitate of Sulfur: Precipitated Milk of Sulfur (S).
Precipitation: The phenomenon in which a solid is formed within a solution and falls to the bottom of the vessel in which the solution was contained.
Primus Metal: See Prince Rupert's Metal
Prince Rupert's Metal (Bath Metal, Primus Metal, Princes Metal): A Brass metal alloy in which the ratios of Copper (Cu) to Zinc (Zn) are approximately 4 to 1.
Prince's Metal: See Prince Rupert's Metal
Principle: One of the simplest forms of matter, from which other substances are formed through combinations with other principles or other combinations of principles. Although there are similarities to the modern term "element", the two are not truly synonymous.
Proximate Principles: Components obtained through the chemical analysis which themselves are compounds but presumed to be simpler than the original substance.
Prussian Blue: Ferric Ferrocyanide (Fe₄[Fe(Cn)₆]₃). Complex salts used in inks and dyes resulting from the oxidation of the white precipitate of a solution of Iron (II) Sulfate, FeSO₄, and Potassium Ferrocyanide, K₄Fe(CN)₆.
Prussian Acid, or Prussic Acid: Hydrocyanic Acid (HCN). [Prout].
Prussiate: A Cyanide, CN^-, Ferricyanide, Fe(CN)₆^3-, or Ferrocyanide, Fe(CN)₆^4-.
Prussiate, Red: Potassium Ferricyanide, K₃Fe(CN)₆.
Prussiate, Yellow: Potassium Ferrocyanide, K₄Fe(CN)₆^.3H₂O.
Pulvis Algarothi: Antimonious Oxychloride (SbOCl).
Pulvis Fulminans: An explosive mixture made from Potassium Nitrate, Potasium Carbonate, and sulfur.
Pumice: A light porous stone of mixed Silicates.
Pure Clay: Alumina. Aluminum Oxide (Al₂O₃).
Pure Ponderous Earth: Baryta. Barium Oxide. (BaO)
Purfication: Any process in which one substance is rendered free, or relatively free, of other substance. Common methods included distillation, crystallization, and precipitation.
Purple of Cassius: Made by Andreas Cassius in 1685 by precipitating a mixture of Gold, Stannous and Stannic Chlorides, with alkali. Used for colouring glass.
Purple Crystals: Potassium Permanganate.
Pyrites: Mineral form of Iron Disulphide. Stable in air.Originally, any mineral which could strike sparks from steel. The term was often used to reference Iron Pyrites (FeS₂). Originally any "fire-stone" from which sparks could be struck; eventually an Iron Sulfide or Iron-Copper Sulfide. [T. Thomson]
Pyroligneous Acid: Crude Acetic Acid distillate from wood (HC₂H₃O₂). Containing Acetic Acid (CH₃COOH), Methanol (CH₃OH), and Acetone (CH₃COCH₃).
Pyroligneous Spirit: Methyl Alcohol (CH₃OH).

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Quadrangular Nitre: Sodium Nitrate (NaNO₃).
Quartation: The process of combining Gold (Au) and Silver (Ag) in the ratio 1:3. When the combination is dissolved in Nitric Acid, the Silver is dissolved and the Gold is separated, free from impurities.
Quartz: A mineral whose primary component is Silicon Dioxide (SiO₂). Its color and other aspects of its appearance depended on the impurities present.
Quicklime: Calcium Oxide (CaO).
Quicksilver: Mercury (Hg). Liquid Mercury metal. [Boyle, Cavendish, Priestley, Torricelli]
Quicksilver Calcined Per Se: Mercuric Oxide (HgO).
Quintessence: A mixture of an essential oil and alcohol.
Quintessence of Lead: Acetone (CH₃COCH₃).

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Rabel's Water: The liquid obtained by macerating poppy flowers in a mixture of Sulphuric Acid and alcohol for some days and then filtering.
Racemic Acid: An optically inactive form of Tartaric Acid consisting of equal quantities of optical isomers. Racemic originally referred to the origin of the acid (grapes), but now (in chemistry) refers to an optically inactive mixture of optically active isomers. [Pasteur].
Ramous: (1) Individual (fundamental) particles of viscous or rigid bodies; (2) branching or filiment-like parts of a liquid mixture.
Rankine Scale: Absolute Temperature Scale (i.e., one in which absolute zero is assigned the value zero) named after the 19th. century Scottish engineer William Rankine and denoted by °R. One Rankine degree is the same size as a Fahrenheit degree, so absolute zero (-460°F) is 0°R, the normal freezing point of water (32°F) is 492°R and the normal boiling point (212°F) is 672°R. (See Celsius Scale, Fahrenheit Scale, Kelvin Scale.).
Realgar (Red Orpiment, Red Arsenic, Ruby Arsenic, Ruby Sulfur): Red or of Arsenic, Arsenic Disulfide (As₂S₂). A native red or orange Arsenic (II) Sulfide, As₂S₂.
Réaumur Scale: Temperature scale devised in 1731 by R. A. F. Réaumur and denoted by °R. The normal freezing point of water is 0°R and the normal boiling point of water is 80°R. (See Celsius Scale, Fahrenheit Scale, Kelvin Scale.) [Lavoisier].
Receiver: The vessel attached to the condensing part of a distillation apparatus in order to receive the condensed products from the distillation.
Recrement: Solid waste or refuse from a chemical operation, e.g., scoria.
Rectification: The purifying or refining of a substance by one or (usually) more distillations.
Red Arsenic (Realgar): Native Arsenic Disulphide (As₂S₂).
Red Bole: A red clay that contained Silicates of Iron and Aluminum. Used as a red pigment and as a base for gilding.
Red Flowers of Antimony: Probably Antimony Sulfide (Sb₂S₅).
Red Ochre: A mineral solid approximately 95 percent red Iron Oxide (Fe₂O₃). An old and important pigment.
Red Precipitate: See Red Precipitate of Mercury.
Red Precipitate of Mercury: Impure Mercuric Oxide (HgO).
Red Prussiate of Potash: Potassium Ferricyanide.
Red Saunders (Red Sanders): The wood from the tree Pterocarpus santalinus, commonly called red sandlewood. Used in dyeing.
Reduction: The returning of a substance to a previous or original condition; e.g., the restoring of a metal to the metallic state from its Oxide.
Refractory Earths: Mineral substances that do not fuse under the action of fire.
Refrigoratory: A vessel at the top or head of some stills that is surrounded by or filled with cold water to condense any vapors in tubes or vessels within it.
Regenerated Marine Salt: Potassium Chloride (KCl).
Regenerated Sea Salt: Potassium Chloride (KCl).
Regenerated Tartar: Potassium Acetate (KC₂H₃O₂). In this form, the compound was made from distilled vinegar and salt of tartar.
Reguline Caustic: Potassium Carbonate (K₂CO₃).
Regulus: The pure form of a metal, e.g., regulus of Antimony. A metal was formerly called the regulus of the ore from which it was reduced [Scheele]; "Regulus" (without further specification) meant Regulus of Antimony (i.e., antimony in modern nomenclature). [Lavoisier]
Reinecke's Acid: Ttetrathiocyanodiammonochromic Acid, HCr(NH₃)₂(SCN)₄.
Reinecke's Salt: An Ammonium Salt of Reinecke's acid, NH₄[Cr(NH₃)₂(SCN)₄]^.H₂O.
Resin of Copper: Cuprous Chloride. Made by Robert Boyle in 1664 by heating Copper with corrosive sublimate.
Retort: A vessel with a long tubular neck bent down at the point where it joins the body of the vessel. Especially suited for the distillation of substances under low heat. Used by chemists and alchemists for distillation and the like. [Black, Cavendish, Lavoisier, Scheele]
Reverberatory Furnace: A furnace constructed so that a sample placed within it is heated from above as well as from the fire beneath it. For example, the furnace may have a top which reflects heat on the sample from the fire below it. [Black, Lavoisier].
Revivification: The restoration of a metal to the metallic state from one of its compounds. Similar to, but broader in scope, than "reduction."
Risigallum: See Rock Alum.
Rochelle Salt (Seignette Salt): Potassium Sodium Tartrate (KNaC₄H₄O₆ ^. 4H₂O), named for the French seaport La Rochelle, where the compound was prepared; also known as Seignette's salt, after the apothecary who first prepared it.
Rock Alum: Usually larger crystals or formations of Potassium Aluminum Sulfate (KAl(SO₄)₂ ^. 12H₂O). Alum of this quality often was imported from Italy.
Rock-Crystal: Pure, colorless, transparent, crystalline quartz occurring naturally in large prismatic crystals. Silicon Dioxide (SiO₂).
Rog: Concentrated native vegetable acid. From the usual preparations, it would be primarily Citric Acid (C₆H₈O₇).
Roman Vitriol: Copper Sulfate (CuSO₄). In Britain this terms was sometimes used for Ferrous Sulfate (FeSO₄).
Röntgen Rays: X-rays, named after their discoverer, Wilhelm Röntgen.
Rouge, Crocus, Colcothar: Red varieties of Ferric Oxide are formed by burning Green Vitriol in air.
Ruby: Red Corundum, Al₂O₃.
Ruby, Blend: Red Sphalerite, Zinc Sulfide, ZnS
Ruby, Copper: Cuprite, Copper (I) Oxide, Cu₂O.
Russian Pot Ash: Potassium Carbonate (K₂CO₃).
Rust of Copper: See Verdigris.