Gram

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Template:Short description Script error: No such module "about". Script error: No such module "redirect hatnote". Template:Use dmy dates Template:Infobox unit The gram (originally gramme;[1] SI unit symbol g) is a unit of mass in the International System of Units (SI) equal to one thousandth of a kilogram.

Originally defined in 1795 as "the absolute weight of a volume of pure water equal to the cube of the hundredth part of a metre [1 cm3], and at the temperature of melting ice",[2] the defining temperature (0 °C) was later changed to the temperature of maximum density of water (approximately 4 °C). Subsequent redefinitions agree with this original definition to within 30 parts per million (0.003%), with the maximum density of water remaining very close to 1 g/cm3, as shown by modern measurements.[3]

By the late 19th century, there was an effort to make the base unit the kilogram and the gram a derived unit. In 1960, the new International System of Units defined a gram as one thousandth of a kilogram (i.e., one gram is Template:Val). The kilogram, as of 2019, is defined by the International Bureau of Weights and Measures from the metre, the second, and from the fixed numerical value of the Planck constant (Template:Mvar).[4][5]

Official SI symbol

The only unit symbol for gram that is recognised by the International System of Units (SI) is "g" following the numeric value with a space, as in "640 g" to stand for "640 grams" in the English language. The SI disallows use of abbreviations such as "gr" (which is the symbol for grains),[6]Template:Rp "gm" ("g⋅m" is the SI symbol for gram-metre) or "Gm" (the SI symbol for gigametre).

History

The word gramme was adopted by the French National Convention in its 1795 decree revising the metric system as replacing the gravet (introduced in 1793 simultaneously with a base measure called grave, of which gravet was a subdivision). Its definition remained that of the mass (then called weight) of a cubic centimetre of water.[7][8]

French gramme was taken from the Late Latin term Script error: No such module "Lang".. This word—ultimately from Greek Script error: No such module "Lang". (grámma), "letter"—had adopted a specialised meaning in Late Antiquity of "one twenty-fourth part of an ounce" (two oboli),[9] corresponding to about 1.14 modern grams. This use of the term is found in the carmen de ponderibus et mensuris ("poem about weights and measures") composed around 400 AD.Template:Efn There is also evidence that the Greek Script error: No such module "Lang". was used in the same sense at around the same time, in the 4th century, and survived in this sense into Medieval Greek,[10] while the Latin term died out in Medieval Latin and was recovered in Renaissance scholarship.Template:Efn

The gram was the base unit of mass in the 19th-century centimetre–gram–second system of units (CGS). The CGS system coexisted with the metre–kilogram–second system of units (MKS), first proposed in 1901, during much of the 20th century, but the gram was displaced by the kilogram as the base unit for mass when the MKS system was chosen for the SI base units in 1960.

Uses

File:Amphetamine.jpg
One gram of amphetamines (the unit often used for street retail)

The gram is the most widely used unit of measurement for non-liquid ingredients in cooking and grocery shopping worldwide.[11][12]Script error: No such module "Unsubst". Liquid ingredients are often measured by volume rather than mass.

Many standards and legal requirements for nutrition labels on food products require relative contents to be stated per 100 g of the product, such that the resulting figure can also be read as a percentage by mass.

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Conversion factors

File:Wellcome Foundation Object Wellcome L0044963.jpg
A container of Wellcome-brand cocaine, containing 1 avoirdupois ounce or 28.3 grams (note the non-standard abbreviation gm.).

Comparisons

See also

Notes

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References

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  1. ↑ Script error: No such module "citation/CS1".
  2. ↑ Script error: No such module "citation/CS1".
  3. ↑ The density of water is Template:Val at Template:Val. See Script error: No such module "citation/CS1".
  4. ↑ Script error: No such module "citation/CS1".
  5. ↑ Decision CIPM/105-13 (October 2016) Template:Webarchive. The day is the 144th anniversary of the Metre Convention.
  6. ↑ National Institute of Standards and Technology (October 2011). Butcher, Tina; Cook, Steve; Crown, Linda et al. eds. "Appendix C – General Tables of Units of Measurement" Template:Webarchive (PDF). Specifications, Tolerances, and Other Technical Requirements for Weighing and Measuring Devices Template:Webarchive. NIST Handbook. 44 (2012 ed.). Washington, D.C.: U.S. Department of Commerce, Technology Administration, National Institute of Standards and Technology. ISSN 0271-4027 Template:Webarchive. OCLC Template:OCLC. Retrieved 30 June 2012.
  7. ↑ Script error: No such module "citation/CS1".
  8. ↑ Convention nationale, décret du 1er août 1793, ed. Duvergier, Collection complète des lois, décrets, ordonnances, règlemens avis du Conseil d'état, publiée sur les éditions officielles du Louvre, vol. 6 (2nd ed. 1834), p. 70 Template:Webarchive. The metre (mètre) on which this definition depends was itself defined as the ten-millionth part of a quarter of Earth's meridian, given in traditional units as 3 pieds, 11.44 lignes (a ligne being the 12th part of an pouce (inch), or the 144th part of a pied.
  9. ↑ Charlton T. Lewis, Charles Short, A Latin Dictionary s.v. "gramma" Template:Webarchive, 1879
  10. ↑ Henry George Liddell. Robert Scott. A Greek-English Lexicon (revised and augmented edition, Oxford, 1940) s.v. γράμμα Template:Webarchive, citing the 10th-century work Geoponica and a 4th-century papyrus edited in L. Mitteis, Griechische Urkunden der Papyrussammlung zu Leipzig, vol. i (1906), 62 ii 27.
  11. ↑ Script error: No such module "citation/CS1".
  12. ↑ Script error: No such module "citation/CS1".
  13. ↑ 5th SI Brochure (1985), p. 78
  14. ↑ Script error: No such module "Citation/CS1".
  15. ↑ Script error: No such module "citation/CS1".
  16. ↑ Script error: No such module "citation/CS1".
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