acidum salis: hydrochloric acid (HCl, marine acid, muriatic acid, spirit of salt); literally "acid of salt". [Scheele]

actinium C: an isotope of bismuth produced in actinium decay, namely 211Bi (half-life = 2 min). See table. [Soddy]

actinium D: an isotope of thallium produced in actinium decay, namely 207Tl (half-life = 5 min). See table. [Soddy 1 & 2]

ad siccum: to dryness, as in evaporation to dryness. [Scheele]

aer fixus: fixed air

aether: ether. Aether nitri, literally "nitric ether", was ethyl nitrate (C2H5NO3) [Scheele].

air: formerly a general term for any gas (elastic fluid). [Black, Cavendish, Priestley]

alkali: a basic substance. Caustic alkalis were usually hydroxides, while mild alkalis were carbonates. (See alkaline air, fossil alkali, marine alkali, mineral alkali, vegetable alkali, volatile alkali.)

alkaline air: ammonia gas (NH3); see spirit of hartshorn, volatile alkali. [Priestley]

alum: double salt of aluminum sulfate with sodium, potassium, or ammonium sulfate (i.e., AlM(SO4)2, where M = Na, K, or NH4). [Black, Lavoisier]

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

aqua regia or aqua regis: a mixture of concentrated nitric and hydrochloric acids capable of dissolving the "royal metal" gold. [Scheele]

aqua vitae: concentrated aqueous ethanol (C2H5OH), typically prepared by distilling wine [Arnald of Villanova] (spirit of wine)

azote: nitrogen, named because it did not support respiration and was therefore "lifeless" (N2, phlogisticated air; see also mephitic air). [Dalton 1 & 2, Lavoisier, Prout, T. Thomson]

barilla: impure sodium carbonate extracted from soap-wort. [Rey]

benzine: ligroin or petroleum ether [Rayleigh]; sometimes benzene (C6H6)

bittern: solution of magnesium salts

black ash: impure sodium carbonate

black lead: graphite, an allotrope of carbon

bleaching powder: calcium chloro-hypochlorite (CaOCl2)

brimstone: sulfur (S). [Boyle]

calcareous earth: calcium oxide (CaO, lime, quicklime). Caustic calcareous earth was calcium hydroxide (Ca(OH)2, slaked lime) and mild calcareous earth was calcium carbonate (CaCO3, chalk, carbonate of lime). [Black, Lavoisier]

calces: See calx.

calcination: formation of a calx, i.e., oxidation of a metal, often by roasting. [Black; Lavoisier 1, 2, & 3; Rey]

caloric: a postulated elastic fluid associated with heat flow. [Avogadro, Dalton, Lavoisier]

calx (plural calces): a metal oxide (earth), the result of roasting a metal or mineral. [Lavoisier 1, Rey, Stahl] Sometimes used for a particular calx, namely lime.

carbonic acid: carbon dioxide (CO2, fixed air) [Dalton; but also Arrhenius, Maxwell, Mendeleev, Rutherford, J. J. Thomson et al.]

carbonic oxide: carbon monoxide (CO) [Dalton, Gay-Lussac, Maxwell, Ramsay, T. Thomson]

carburetted hydrogen: methane (CH4) [Dalton, Prout]

Celsius scale: temperature scale devised in the early 18th century by a certain Elvius from Sweden (1710), a Christian of Lyons (1743), and the botanist Linnaeus (1740), apparently independently. Temperatures on this scale are denoted by °C. The normal freezing point of water is 0°C and the normal boiling point of water is 100°C. The scale was named after Anders Celsius who proposed a similar scale in 1742, but designating the freezing point to be 100 and the boiling point to be 0. The scale is sometimes also called the Centigrade scale. (See Fahrenheit scale, Kelvin scale, Réaumur scale.)

Centigrade scale: See Celsius scale.

ceruse: lead carbonate (PbCO3)

chalk: calcium carbonate (CaCO3, carbonate of lime, mild calcareous earth). [Lavoisier 1 & 2; Priestley; T. Thomson]

colcothar: iron (III) oxide (Fe2O3) by-product from sulfuric acid manufacture [Lavoisier]

copperas: iron (II) sulfate (FeSO4.7H2O, green vitriol)

corrosive sublimate of mercury: mercuric chloride (HgCl2). [Scheele]

creech: calcium sulfate (CaSO4)

dephlogisticated air: oxygen (O2, pure air, vital air); see phlogiston. [Cavendish, Ingenhousz, Lavoisier 1 & 2, Priestley 1 & 2, Watt]

dephlogisticated marine acid: chlorine (Cl2, oxymuriatic acid). See marine acid. [Priestley, Scheele]

didymium: a mixture of praseodymium (Pr) and neodymium (Nd) believed to be an element until 1885. [Mendeleev, Newlands]

earth: a metal oxide (calx); see calcareous earth, magnesian earth, siliceous earth. [Dalton, Priestley, Scheele, T. Thomson]

elastic fluid: usually a descriptive term for gas (air) [Black, Dalton, Gay-Lussac, Lavoisier, T. Thomson et al.]; however, certain elastic fluids were postulated which correspond to no material (caloric, ether, phlogiston).

emanation: a radioactive gas (radon) produced in the decay of other radio-active elements. Specifically, thorium emanation (also thoron) is 220Rn (half life = 55 s) produced from the decay of thorium; radium emanation is 222Rn (half life = 3.8 d) produced from the decay of radium; actinium emanation is 219Rn (half life = 4 s). See table. [Rutherford 1 & 2, Soddy 1 & 2]

ether (or aether; sometimes luminiferous ether): a hypothetical elastic fluid postulated to support the transmission of light. [Röntgen, J. J. Thomson 1 & 2]

Fahrenheit scale: temperature scale devised in 1717 by G. D. Fahrenheit and denoted by °F. The normal freezing point of water is 32°F and the normal boiling point of water is 212°F. (See Celsius scale, Kelvin scale, Réaumur scale.)

fixed air (aer fixus): carbon dioxide (CO2, carbonic acid). [Black, Cavendish, Priestley, Scheele et al.]

fluoro acid air: silicon tetrafluoride (SiF4) [Priestley].

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

funiculus: an invisible membrane postulated to hold up a column of mercury in the Torricellian experiment [Linus]

galena: native lead sulfide (PbS), or lead or silver ore, or the slag remaining after refining lead.

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

glucinium or glucinum: beryllium (Be). [Newlands, Ramsay]

grain : unit of mass. For late 18th-century French system, see livre. [Lavoisier]

gros: Unit of mass in late 18th-century France; see livre. [Lavoisier 1 & 2]

hepar: sulfide (sulphuret)

hepatic air: hydrogen sulfide (H2S, sulphuretted hydrogen)

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. [Lavoisier 1 & 2]

inflammable air: hydrogen (H2). [Cavendish, Franklin, Priestley, Watt et al.]

ionium: an isotope of thorium produced in uranium decay, namely 230Th (half-life = 80 kyr). See table. [Boltwood 1907; Soddy 1, 2, & 3]

kelp: impure sodium carbonate from seaweed

Kelvin scale: an absolute temperature scale (i.e., one in which absolute zero is assigned the value zero) named after William Thomson, first Baron of Kelvin, who first proposed an absolute temperature scale. One Kelvin (denoted simply K or sometimes °K) is the same size as a Celsius degree, so the normal boiling point of water is 273.15 K and the normal boiling point is 373.15 K. (See Celsius scale, Fahrenheit scale, Réaumur scale.)

ligne: Unit of length in late 18th-century France; see pied. [Lavoisier]

lime: calcium oxide (CaO, calcareous earth, quicklime). Carbonate of lime was calcium carbonate (CaCO3, mild calcareous earth, chalk), and slaked lime calcium hydroxide (Ca(OH)2, caustic calcareous earth). [Dalton, Lavoisier, Priestley, Ramsay et al.]

lime-water: a saturated aqueous solution of calcium hydroxide (Ca(OH)2). [Black, Dalton, Lavoisier, Ramsay et al.]

litharge: lead (II) oxide (PbO). [Priestley]

liver of sulfur: calcium sulfide (CaS) [Cavendish, Priestley, Stahl]

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. [Lavoisier]

lye: potassium hydroxide solution (KOH)