magnesia etc.: Magnesia alba [Black] (literally "white magnesia") was magnesium carbonate (MgCO3), also known as mild magnesian earth. The metal present in this compound is magnesium, but was named magnium by Davy to avoid confusion with another magnesia. Magnesia nigra (literally "black magnesia") was the mineral pyrolusite, natural manganese dioxide (MnO2), sometimes also called simply magnesia or manganese [Scheele]. Eventually manganese became the name of the metal present in the mineral.

manganese: See magnesia etc.

marine acid: hydrogen chloride solution (HCl, acidum salis, muriatic acid, spirit of salt). Gaseous HCl was marine acid air. [Cavendish, Lavoisier, Priestley, Scheele]

marine alkali: sodium carbonate (common mineral alkali, fossil alkali, soda)

mephitic air: nitrogen (N2, azote, phlogisticated air) or carbon dioxide (CO2, carbonic acid, fixed air)

mercurius calcinatus per se: mercuric oxide (HgO, precipitated mercury per se, red precipitate). [Priestley, Watt]

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. [Hahn, Soddy 1 & 2]

mineral alkali, common: hydrated sodium carbonate (fossil alkali, marine alkali, soda)

minium: a lead oxide (Pb3O4, red lead). [Lavoisier, Priestley]

muriate: chloride; see muriatic acid. [Gay-Lussac, T. Thomson]

muriatic acid: hydrochloric acid (HCl, acidum salis, marine acid, spirit of salt); muriatic gas is gaseous HCl. [Black, Gay-Lussac, Prout, Scheele, T. Thomson]

nitre or niter: potassium nitrate (KNO3, saltpeter). Black gunpowder was made from nitre, charcoal, and sulfur. [Cavendish, Lavoisier, Priestley, Rayleigh, Watt]

nitric acid: nitrogen dioxide (NO2) [Avogadro, Dalton, Gay-Lussac, Lavoisier et al.] or nitrogen pentoxide (N2O5) [Prout]

nitrous acid: 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 NO2, N2O4, N2O5 [Dalton].

nitrous air: nitric oxide (NO, nitrous gas) [Cavendish, Priestley 1 & 2]

nitrous gas: specifically nitric oxide (NO, nitrous air) [Avogadro, Dalton, Gay-Lussac, T. Thomson]; or a mixture of nitrogen oxides such as that produced by the action of nitric acid on a metal in the presence of air

oil of vitriol or oil of sulfur per campanum or spirit of vitriol (spiritus vitrioli): sulfuric acid (H2SO4, vitriolic acid). [Black, Lavoisier, Scheele, Stahl]

olefiant gas: ethene (C2H4) [Dalton, Prout, T. Thomson]

once: Unit of mass in late 18th-century France; see livre. [Lavoisier]

oxymuriatic acid: chlorine (Cl2, dephlogisticated marine acid); named on the belief that it was a compound of oxygen and HCl (muriatic acid)

pearl ash: potassium carbonate (K2CO3)

phlogisticated air: nitrogen (N2, azote) [Cavendish, Lavoisier, Priestley 1 & 2, Watt]

phlogisticated nitrous air: nitrous oxide (N2O); see nitrous air. [Priestley]

phlogiston: 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.]

pied: 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]

pinte: volume unit in late 18th-century France, equal to 2.01508 English pints, 58.145 cubic inches, or 0.953 liters. [Lavoisier]

plaster of paris: calcium sulfate (Ca(SO4)2.H2O)

plumbago: a lead ore, including lead oxide (litharge) or lead sulfide (galena); or graphite (black lead). [Lavoisier, Priestley]

potash: crude or purified potassium carbonate (K2CO3, vegetable alkali, pearl ash) leached from the ashes of plant material, or crude sodium carbonate, or potassium hydroxide (KOH, lye). [Dalton, Rayleigh, T. Thomson et al.]

pouce: Unit of length in late 18th-century France; see pied.

precipitated mercury per se or precipitate per se: mercuric oxide (HgO, mercurius calcinatus per se, red precipitate) [Lavoisier, Priestley]

prussic acid: hydrocyanic acid (HCN) [Berthollet, Gay-Lussac, Prout]

pure air: oxygen (O2, dephlogisticated air, vital air). [Lavoisier, Priestley, Watt]

pyrite or pyrites: 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 from wood

quicklime: calcium oxide (CaO, calcareous earth, lime). [Black, Lavoisier, Priestley]

quicksilver: liquid mercury metal. [Boyle, Cavendish, Priestley, Torricelli]

radioactinium: a radioactive isotope of thorium produced in actinium decay, namely 227Th (half life = 19 d). [Soddy 1 & 2]

radio-elements: For occurrences before 1913 (i.e., before the concept of isotopy), radioisotopes is often a more appropriate modern term. See table. [Soddy 1, 2, 3]

radiolead: a radioactive isotope of lead produced in uranium decay, namely 210Pb (half life = 21 y). Also radium D. See table.

radiotellurium: An isotope of polonium produced in uranium decay, namely 210Po (half life = 140 d). [Markwald] Also called radium F. See table.

radiothorium: an isotope of thorium produced in thorium decay, namely 228Th (half-life = 1.9 y). [Hahn & Ramsay, Soddy 1 & 2]. See table.

radium A: an isotope of polonium produced in uranium decay, namely 218Po (half-life = 3 min). [Rutherford & Royds]

radium C: There were three isotopes whose designation included radium C, all of which occur in uranium decay. Simple radium C is an isotope of bismuth, namely 214Bi (half-life = 20 min). [Rutherford 1, 2, & 3] Radium C' is an isotope of polonium, namely 214Po; it is the major decay product of radium C. Radium C2 is an isotope of thallium, namely 210Tl (half-life = 1.3 min); it is a minor decay product of radium C. [Soddy] See table.

radium D: See radiolead. [Soddy 1 & 2]

radium F: See radiotellurium.

radium G: The isotope of lead which is the end-product of uranium/radium decay, namely 206Pb. See table.

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]

red precipitate: mercuric oxide (HgO, mercurius calcinatus per se, precipitated mercury per se). One way of preparing red precipitate was by mixing mercury with nitric acid, evaporating, and heating the residual mercuric nitrate. Since precipitation from nitric acid was a different method of preparation than calcination, the author did not necessarily know that the product was the same in both cases, so the author may not regard red precipitate as synonymous with mercurius calcinatus per se. [Priestley]

red lead: a lead oxide (Pb3O4, minium). [Priestley]

retort: a container with a long tubular neck 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]

saccharum saturni: sugar of lead

sal ammoniac: ammonium chloride (NH4Cl). [Black, Scheele]

sal commune: common salt, i.e., sodium chloride (NaCl). [Scheele]

sal enixum: potassium sulfate (K2SO4)

sal mirabilis: sodium sulfate (Na2SO4.10H2O, Glauber's salt)

saltpeter or saltpetre: potassium nitrate (KNO3, nitre). [T. Thomson]

siliceous earth: silicon dioxide (SiO2). [Lavoisier, Scheele]

soda: sodium carbonate (Na2CO3, washing soda) or sodium hydrogen carbonate (NaHCO3, baking soda) [Dalton, Lavoisier, Prout, Rayleigh]. Caustic soda was sodium hydroxide (NaOH) [Mendeleev]. See also fossil alkali, marine alkali, common mineral alkali.

Spanish white: bismuth oxychloride (BiOCl) or oxynitrate (BiONO3)

spirit (spiritus): an essence or extract that can be prepared from another substance as by distillation

spirit of hartshorn: ammonia (NH3) or its aqueous solution (formerly prepared from animal horns or hooves); see alkaline air, volatile alkali. [Black]

spirit of nitre: nitric acid (HNO3, aqua fortis, nitrous acid). [Cavendish, Priestley]

spirit of salt (spiritus salis): hydrochloric acid (HCl, acidum salis, marine acid, muriatic acid). [Black, Scheele]

spirit of vitriol (spiritus vitrioli): See oil of vitriol [Black, Scheele].

spirit of wine (spiritus vini): concentrated aqueous ethanol (C2H5OH), typically prepared by distilling wine; see aqua vitae. [Scheele]

sugar of lead (saccharum saturni: lead acetate (Pb(CH3CO)2)

sulphuret: sulfide (hepar). [Dalton, T. Thomson]

sulphuretted hydrogen: hydrogen sulfide (H2S, hepatic air). [Dalton,

Gay-Lussac, Prout, T. Thomson]

sulphuric acid: sulfur trioxide (SO3). [Dalton, Gay-Lussac, Lavoisier, Prout, T. Thomson]

sulphurous acid or sulphurous gas: sulfur dioxide (SO2). [Gay-Lussac, Lavoisier, Prout, T. Thomson]

tartar or tartar of wine: potassium hydrogen tartrate (KHC4H4O6), cream of tartar (cremor tartari) when purified into small white crystals. [Stahl] Tartar emetic is potassium antimonyl tartrate.

thorium A: an isotope of polonium produced in thorium decay, namely 216Po (half-life = 0.15 s). See table. [Soddy]

thorium C: The names of two radioisotopes, both produced in thorium decay, included thorium C. Simple thorium C was an isotope of bismuth, namely 212Bi (half-life = 61 min); thorium C' was an isotope of polonium, namely 212Po (half-life = 0.3 µs). See table. [Rutherford, Soddy]

thorium D: an isotope of thallium produced in thorium decay, namely 208Tl (half-life = 3 min). See table. [Soddy 1 & 2]

thorium X: an isotope of radium produced in thorium decay, namely 224Ra (half-life = 3.6 d). See table. [Rutherford, Soddy]

trona: natural sodium carbonate (Na2CO3.NaHCO3)

uranium II: an isotope of uranium produced in uranium decay, namely 234U (half-life = 2.5x105 y). Uranium I is simply the most abundant isotope of uranium, 238U. See table. [Soddy 1, 2, & 3]

uranium X: There were two uranium X produced in uranium decay. Uranium X1 (simply uranium X before the discovery of uranium X2) was an isotope of thorium, namely 234Th (half-life = 24 d); uranium X2 was an isotope of protactinium 234Pa. See table. [Crookes; Soddy 1, 2, & 3]

vegetable alkali: crude or purified potassium carbonate (K2CO3, pearl ash). Sometimes specified as mild vegetable alkali or fixed vegetable alkali.

vital air: oxygen (O2, dephlogisticated air, pure air). [Lavoisier]

vitriol: a sulfate, especially iron sulfate. Blue vitriol was copper sulfate (CuSO4.5H2O), green vitriol was iron (II) sulfate (FeSO4.7H2O, copperas), and white vitriol was zinc sulfate (ZnSO4.7H2O). [Scheele]

vitriolic acid: sulfuric acid (H2SO4, oil of vitriol). Vitriolic acid air (and sometimes vitriolic acid) was sulfur dioxide (SO2). [Black, Cavendish, Lavoisier, Priestley]

volatile alkali: aqueous ammonia (NH3); see alkaline air, spirit of hartshorn. Concrete volatile alkali refers to ammonium carbonate ((NH4)2CO3). [Black, Cavendish, Lavoisier, Scheele]

white lead: lead carbonate (2PbCO3.Pb(OH)2)