The Baumé scale is a pair of

hydrometer A hydrometer or lactometer is an instrument used for measuring density or relative density of liquids based on the concept of buoyancy. They are typically calibrated and graduated with one or more scales such as specific gravity. A hydrometer ...

scales developed by French pharmacist Antoine Baumé in 1768 to measure

density Density (volumetric mass density or specific mass) is the substance's mass per unit of volume. The symbol most often used for density is ''ρ'' (the lower case Greek letter rho), although the Latin letter ''D'' can also be used. Mathematical ...

of various liquids. The unit of the Baumé scale has been notated variously as ''degrees Baumé'', ''B°'', ''Bé°'' and simply Baumé (the accent is not always present). One scale measures the density of liquids heavier than water and the other, liquids lighter than water. The Baumé of

distilled water Distilled water is water that has been boiled into vapor and condensed back into liquid in a separate container. Impurities in the original water that do not boil below or near the boiling point of water remain in the original container. Thus, di ...

is 0. The

API gravity The American Petroleum Institute gravity, or API gravity, is a measure of how heavy or light a petroleum liquid is compared to water: if its API gravity is greater than 10, it is lighter and floats on water; if less than 10, it is heavier and sinks ...

scale is based on errors in early implementations of the Baumé scale.

Definitions

Baumé degrees (heavy) originally represented the percent by mass of sodium chloride in water at . Baumé degrees (light) was calibrated with 0°Bé (light) being the density of 10% NaCl in water by mass and 10°Bé (light) set to the density of water. Consider, at near room temperature: * +100°Bé (specific gravity, 3.325) would be among the ''densest'' fluids known (except some liquid metals), such as

diiodomethane Diiodomethane or methylene iodide, commonly abbreviated "MI", is an organoiodine compound. Diiodomethane is a colorless liquid; however, it decomposes upon exposure to light liberating iodine, which colours samples brownish. It is slightly solub ...

. * Near 0°Bé would be approximately the density of water. * −100°Bé (specific gravity, 0.615) would be among the ''lightest'' fluids known, such as liquid

butane Butane () or ''n''-butane is an alkane with the formula C4H10. Butane is a gas at room temperature and atmospheric pressure. Butane is a highly flammable, colorless, easily liquefied gas that quickly vaporizes at room temperature. The name but ...

. Thus, the system could be understood as representing a practical spectrum of the density of liquids between −100 and 100, with values near 0 being the approximate density of water.

Conversions

The relationship between specific gravity (s.g.; i.e., water-specific gravity, the density relative to water) and degrees Baumé is a function of the temperature. Different versions of the scale may use different reference temperatures. Different conversions formulae can therefore be found in various handbooks. As an example, a 2008 handbook states the conversions between specific gravity and degrees Baumé at a temperature of : :

\displaystyle\frac &\text \end \end

The numerator in the specific gravity calculation is commonly known as the "modulus". An older handbookSmithells, Colin J. and Al. 'Metals Reference Book', London Butterworths Scientific Publications, 1949. Page 41 gives the following formulae (no reference temperature being mentioned): :

\displaystyle\frac &\text \end

Other scales

Because of vague instructions or errors in translation a large margin of error was introduced when the scale was adopted. The

scale is a result of adapting to the subsequent errors from the Baumé scale. The Baumé scale is related to the Balling, Brix,

Plato Plato ( ; grc-gre, Πλάτων ; 428/427 or 424/423 – 348/347 BC) was a Greek philosopher born in Athens during the Classical period in Ancient Greece. He founded the Platonist school of thought and the Academy, the first institution ...

and '

specific gravity Relative density, or specific gravity, is the ratio of the density (mass of a unit volume) of a substance to the density of a given reference material. Specific gravity for liquids is nearly always measured with respect to water (molecule), wa ...

times 1000' scales.

Use

Before standardization on

around the time of

World War II World War II or the Second World War, often abbreviated as WWII or WW2, was a world war that lasted from 1939 to 1945. It involved the vast majority of the world's countries—including all of the great powers—forming two opposin ...

the Baumé scale was generally used in industrial chemistry and

pharmacology Pharmacology is a branch of medicine, biology and pharmaceutical sciences concerned with drug or medication action, where a drug may be defined as any artificial, natural, or endogenous (from within the body) molecule which exerts a biochemica ...

for the measurement of density of liquids. Today the Baumé scale is still used in various industries such as sugar beet processing, ophthalmics,

starch Starch or amylum is a polymeric carbohydrate consisting of numerous glucose units joined by glycosidic bonds. This polysaccharide is produced by most green plants for energy storage. Worldwide, it is the most common carbohydrate in human diets ...

industry, winemaking, industrial water treatment, and printed circuit board (PCB) fabrication. It is also used for caustic in refining process.

Definitions

Conversions

Other scales

Use

See also

Notes

References

Further reading