A heavy liquid is a solution or liquid chemical substance with a high density and a relatively low viscosity. Heavy liquids are often used for determination of density in mineralogy, for density gradient centrifugation and for separating mixtures.
Uses
Common applications of heavy liquids include: Density gradient centrifugation Separating mixtures and sink/swim analysis Flotation process Determination of density
Toxicity
The classical heavy liquids like 1,1,2,2-tetrabromoethane (Muthmann's solution), potassium tetraiodomercurate(II) (Thoulet's solution), bromoform, or diiodomethane which are used in mineralogy are very toxic.
These toxic chemicals are avoided today in consideration of the fact that there are alternative water-based, non-toxic heavy liquids like sodium polytungstate solutions.Callahan J, A non-toxic heavy liquid and inexpensive filters for separation of mineral grains, in Journal of Sedimentary Petrology, 57/1987, S.765-6 With this relatively new heavy liquid, densities up to 3.1 g·cm−3 can be adjusted . Adding parts of pulverulent tungsten carbide increases the density to 4.6 g·cm−3.CD Römpp Chemie Lexikon – Version 1.0: Schwerflüssigkeiten, Georg Thieme Verlag, 1995
List of common heavy liquids with density > 2.0 g·cm−3
Name Density (g·cm−3) 1,2-Dibromoethane 2.180 cis-1,2-Dibromoethene 2.246 trans-1,2-Dibromoethene 2.231 Dibromomethane 2.477 Bromal 2.550 Bromoform 2.890 1,1,2,2-Tetrabromoethane (Muthmanns solution) 2.967 Sodium polytungstate 3.100 Bromine 3.1028 Thoulets solution 3.196 Diiodomethane 3.325 Indium(III) iodide 3.40 Barium tetraiodomercurate(II) (Rohrbach's solution) 3.57 Thallium formate + thallium malonate (Clerici solution) 4.25 Galinstan (gallium, indium, tin alloy) 6.44 Mercury 13.6
Mercury is the heaviest liquid at room temperature. But the heaviest liquid irrespective of temperature is liquid osmium (a rare metal) at its melting point (3033°C/5491.4°F), with a density of 22.59 g·cm−3, 1.65 times as heavy as mercury.See: https://www.aqua-calc.com/calculate/volume-to-weight/substance/liquid-blank-osmium
References
Literature Schnitzer W, Zur Problematik der Schwermineralanalyse am Beispiel triassischer Sedimentgesteine, in International Journal of Earth Sciences, 72/1983, S.67–75, ISSN 1437-3254 (Print) 1437-3262 (Online) Boenigk, Schwermineralanalyse, S.6–15, Stuttgart: Enke, 1983. Ney, Gesteinsaufbereitung im Labor, S.92–113, Stuttgart: Enke, 1986.
External links General information about non-toxic heavy liquids