Editing Grain (unit) (section)

== Current usage ==
[[Image:148 grain 38 special.jpg|thumb|250px|A box of [[.38 Special]] ({{convert|0.357|in|mm|disp=out}}) cartridges that have {{convert|148|gr|g|adj=on}} bullets]]

Grains are commonly used to measure the mass of bullets and [[propellant]]s.<ref>{{cite web |ref= {{sfnref|IPSC Rules|2019}} |url= http://www.ipsc.org/pdf/RulesHandgun.pdf |title= Handgun Competition Rules |edition= January 2019 |author= [[International Practical Shooting Confederation]] |date= 2019 |publisher= International Practical Shooting Confederation |location= Mallorca, Spain |page= 40 |access-date= 2024-10-13}}</ref><ref name="MeyerEtAl2007">{{cite book |last1= Meyer |first1= Rudolf |last2= Köhler |first2= Josef |last3= Homburg |first3= Axel |date= 2007 |title= Explosives |url= https://books.google.com/books?id=ATiYCfo1VcEC |access-date= 4 July 2012 |edition= Sixth, completely revised |publisher= [[Wiley-VCH]] |location= Weinheim, Germany |isbn= 978-3-527-31656-4 |oclc= 255797039 |page= 152 |chapter= Grain |chapter-url= https://books.google.com/books?id=ATiYCfo1VcEC&pg=PA152}}</ref> In archery, the grain is the standard unit used to weigh arrows.<ref>{{cite book |last= Sorrells |first= Brian J. |title= Beginner's Guide to Traditional Archery |url= https://books.google.com/books?id=P5miJc4EbYwC |access-date= 4 July 2012 |edition= 1st |date= 2004 |publisher= [[Stackpole Books]] |location= Mechanicsburg, Pennsylvania |isbn= 978-0-8117-3133-1 |oclc= 474105699 |page= 23 |chapter= The Right Equipment |chapter-url= https://books.google.com/books?id=P5miJc4EbYwC&pg=PA23 |quote= Arrow weight is measured in grains}}</ref>

In North America, the [[hardness of water]] is often measured in [[grains per U.S. gallon]] ({{abbr|gpg}}) of [[calcium carbonate]] equivalents.<ref name="WistEtAl2007">{{cite book |last1= Wist |first1= William |last2= McEachern |first2= Rod |last3= Lehr |first3= Jay H. |date= 2009 |title= Water Softening with Potassium Chloride: Process, Health, and Environmental Benefits |url= https://books.google.com/books?id=GJbdjEvQd1kC |access-date= 4 July 2012 |publisher= [[John Wiley & Sons]] |location= Hoboken, New Jersey |isbn= 978-0-470-08713-8 |oclc= 496960317 |page= 116 |chapter= Chapter 8: Comparison of KCl and NaCl as Regenerant |chapter-url= https://books.google.com/books?id=GJbdjEvQd1kC&pg=PA116}}</ref><ref name="VaclavikEtAl2008">{{cite book |last1= Vaclavik |first1= Vickie A. |last2= Christian |first2= Elizabeth W. |date= 2008 |chapter-url= https://books.google.com/books?id=iCCsvwZrguUC&pg=PA29 |chapter= Chapter 2: Water — Water Hardness and Treatments |title= Essentials of Food Science |edition= 3rd |editor-last= Heldman |editor-first= Dennis R. |editor-link= Dennis R. Heldman |series= Food Science Text Series |location= New York; London |publisher= [[Springer Science+Business Media|Springer]] |page= 29 |isbn= 978-0-387-69939-4 |oclc= 230744052}}</ref> Otherwise, water hardness is measured in the dimensionless unit of [[parts per million]] ({{abbr|ppm}}), numerically equivalent to concentration measured in milligrams per litre.<ref name="WistEtAl2007" /><ref name="VaclavikEtAl2008" /> One grain per U.S. gallon is approximately {{val|17.1|u=ppm}}.<ref name="WistEtAl2007" />{{NoteTag|The exact value of one grain per U.S. gallon is {{sfrac|{{val|64.79891}}|{{val|3.785411784}}}}&nbsp;mg/L (ppm).<ref name="NIST" />{{rp|C-12, C-14}} }} Soft water contains {{val|1|–|4|u=gpg}} of calcium carbonate equivalents, while hard water contains {{val|11|–|20|u=gpg}}.<ref name="VaclavikEtAl2008" />

[[Image:5 grain aspirin.jpg|thumb|250px|A five-grain aspirin. The usage guidance label on a bottle of aspirin indicates that the dosage is "325&nbsp;mg (5&nbsp;gr)".]]
Though no longer recommended, in the U.S., grains are still used occasionally in medicine as part of the [[apothecaries' system]], especially in prescriptions for older medicines such as [[aspirin]] or [[phenobarbital]].<ref name="Zentz2010">{{cite book |last= Zentz |first= Lorraine C. |date= 2010 |title= Math for Pharmacy Technicians |url= https://books.google.com/books?id=PvriGp6ZEhMC |access-date= 5 July 2012 |publisher= [[Jones & Bartlett Learning]] |location= Sudbury, Massachusetts |isbn= 978-0-7637-5961-2 |oclc= 421360709 |pages= 7–8 |chapter= Chapter 1: Fundamentals of Math — Apothecary System |chapter-url= https://books.google.com/books?id=PvriGp6ZEhMC&pg=PA7}}</ref><ref name="Boyer2009">{{cite book |last= Boyer |first= Mary Jo |date= 2009 |title= Math for Nurses: A Pocket Guide to Dosage Calculation and Drug Preparation |url= https://books.google.com/books?id=FCfCGwqNt4QC |access-date= 2 July 2012 |edition= 7th |publisher= [[Wolters Kluwer Health]] / [[Lippincott Williams & Wilkins]] |location= Philadelphia |isbn= 978-0-7817-6335-6 |oclc= 181600928 |pages= 108–109 |chapter= Unit 2 Measurement Systems: The Apothecary System |chapter-url= https://books.google.com/books?id=FCfCGwqNt4QC&pg=PA108}}</ref> For example, the dosage of a standard {{val|325|u=mg}} tablet of aspirin is sometimes given as {{val|5|u=grains}}.<ref name="Zentz2010" /><ref name="Howell2010">{{cite book |last= Howell |first= David C. |date= 2010 |title= Statistical Methods for Psychology |url= https://books.google.com/books?id=5WFohzuwzP0C |access-date= 5 July 2012 |edition= 7th |publisher= Wadsworth, [[Cengage Learning]] |location= Belmont, California |isbn= 978-0-495-59784-1 |oclc= 689547756 |page= 402 |chapter= Chapter 12: Multiple Comparisons Among Treatment Means — 12.10&nbsp;Trend Analysis |chapter-url= https://books.google.com/books?id=5WFohzuwzP0C&pg=PA402}}</ref> In that example the grain is approximated to {{val|65|u=mg}}, though the grain can also be approximated to {{val|60|u=mg}}, depending on the medication and manufacturer.<ref name="Zentz2010" /><ref name="Buchholz2009" /> The apothecaries' system has its own system of notation, in which the units symbol or abbreviation is followed by the quantity in lower case [[Roman numerals]].<ref name="Boyer2009" /><ref name="Buchholz2009">{{cite book |last1= Buchholz |first1= Susan |last2= Henke |first2= Grace |date= 2009 |title= Henke's Med-Math: Dosage Calculation, Preparation and Administration |url= https://books.google.com/books?id=ZlKqGHGNrtIC |access-date= 5 July 2012 |edition= 6th |publisher= [[Wolters Kluwer Health]] / [[Lippincott Williams & Wilkins]] |location= Philadelphia |isbn= 978-0-7817-7628-8 |oclc= 181600929 |pages= 55–6 |chapter= Chapter 3: Metric, Apothecary, and Household Systems of Measurement — Apothecary System |chapter-url= https://books.google.com/books?id=ZlKqGHGNrtIC&pg=PA55}}</ref><ref name="PickarEtAl2012">{{cite book |last1= Pickar |first1= Gloria D. |last2= Swart |first2= Beth |last3= Graham |first3= Hope |last4= Swedish |first4= Margaret |date= 2012 |title= Dosage Calculations |url= https://books.google.com/books?id=wFEsup6KhuQC |access-date= 5 July 2012 |edition= 2nd Canadian |publisher= Nelson Education |location= Toronto |isbn= 978-0-17-650259-1 |oclc= 693657704 |pages= 527–528 |chapter= Appendix B: Apothecary System of Measurement |chapter-url= https://books.google.com/books?id=wFEsup6KhuQC&pg=PA527}}</ref> For amounts less than one, the quantity is written as a fraction, or for one half, ss (or variations such as ss., ṡṡ, or s̅s̅).<ref name="Boyer2009" /><ref name="Buchholz2009" /><ref name="PickarEtAl2012" /><ref name="Biblis1992">{{cite book |editor-last= Biblis |editor-first= Margaret M. |date= 1992 |title= Dorland's Medical Abbreviations |url= https://books.google.com/books?id=iFZqAAAAMAAJ |access-date= 5 July 2012 |publisher= [[Saunders (publisher)|Saunders]] |location= Philadelphia |isbn= 978-0-7216-3751-8 |oclc= 246565261}}</ref>{{rp|263}} Therefore, a prescription for tablets containing 325&nbsp;mg of aspirin and 30&nbsp;mg of codeine can be written "ASA gr. v c̄ cod. gr. ss tablets" (using the medical abbreviations ASA for acetylsalicylic acid [aspirin],<ref name="Biblis1992" />{{rp|34}}<ref name="Steen1971">{{cite book |last= Steen |first= Edwin Benzel |date= 1971 |title= Medical Abbreviations |url= https://books.google.com/books?id=LWvKBnlAY_4C |access-date= 5 July 2012 |edition= 3rd |publisher= [[F.A. Davis]] |location= Philadelphia |isbn= 978-0-7020-0360-8 |oclc= 165344}}</ref>{{rp|8}} c̄ for "with",<ref name="Biblis1992" />{{rp|56}}<ref name="Steen1971" />{{rp|14}} and cod. for codeine).<ref name="Biblis1992" />{{rp|70}}<ref name="Steen1971" />{{rp|19}} The apothecaries' system has gradually been replaced by the metric system, and the use of the grain in prescriptions is now rare.<ref name="Buchholz2009" />

In the U.S., [[Particulate emissions|particulate emission]] levels, used to monitor and regulate pollution, are sometimes measured in grains per cubic foot instead of the more usual {{abbr|ppm|parts per million}} by volume.<ref name="Averdieck2005">{{cite book |last= Averdieck |first= William J. |editor1-first= Randy D. |editor1-last= Down |editor2-first= Jay H. |editor2-last= Lehr |date= 2005 |title= Environmental Instrumentation and Analysis Handbook |url= https://books.google.com/books?id=6jhELyGJOm0C |access-date= 5 July 2012 |publisher= [[Wiley-Interscience]] |location= Hoboken, New Jersey |isbn= 978-0-471-46354-2 |oclc= 469979932 |page= 330 |chapter= 15: Continuous Particulate Monitoring |chapter-url= https://books.google.com/books?id=6jhELyGJOm0C&pg=PA330}}</ref><ref>{{cite encyclopedia |editor-first= Craig L. |editor-last= Chase |date= 1998 |title= Particulate Emissions |encyclopedia= Biomass Energy: A Glossary of Terms |url= https://books.google.com/books?id=NT3JvB4JWYUC |access-date=5 July 2012 |series= Western Regional Biomass Energy Program |publisher= DIANE Publishing |isbn= 978-0-7881-7256-4 |oclc= 256903828 |page= 40 |entry-url= https://books.google.com/books?id=NT3JvB4JWYUC&pg=PA40 }}</ref> This is the same unit commonly used to measure the amount of moisture in the air, also known as the [[absolute humidity]].<ref name="BOEMRE2010">{{cite web |url= http://www.boemre.gov/glossary/aa-ab.htm |title= Glossary: AA–AB |access-date= 5 July 2012 |date= 17 September 2010 |work= Offshore Energy and Minerals Management |publisher= [[Bureau of Ocean Energy Management, Regulation and Enforcement]], [[United States Department of the Interior]] |location= Washington, D.C. |url-status= dead |archive-url= https://web.archive.org/web/20120729121218/http://www.boemre.gov/glossary/aa-ab.htm |archive-date= 29 July 2012 }}</ref> The [[SI]] unit used to measure particulate emissions and absolute humidity is mg/[[Cubic metre|m{{sup|3}}]].<ref name="Averdieck2005" /><ref name="BOEMRE2010" /> One grain per cubic foot is approximately {{val|2288|u=mg/m{{sup|3}}}}.{{NoteTag|The exact value of one grain per cubic foot is {{sfrac|{{val|64.79891}}| {{val|0.028316846592}}}}&nbsp;mg/m<sup>3</sup>.<ref name="NIST" />{{rp|C-10, C-14}} }}