[USMA:22859] RE: Mishmash of units at the liquor store

[Bill Potts]

The SI brochure is somewhat ambiguous regarding whether or not liter is pure SI.   On the one hand, it refers to it as a non-SI unit, accepted for use with SI. On the other hand, it says the following (note item 2):   12th CGPM, 1964, Resolution 6 (CR, 93): litre The 12th Conférence Générale des Poids et Mesures (CGPM), c o n s i d e r i n g Resolution 13 adopted by the 11th CGPM in 1960 and the Recommendation adopted by the Comité International des Poids et Mesures in 1961, 1. abrogates the definition of the litre given in 1901 by the 3rd CGPM, 2. declares that the word "litre" may be employed as a special name for the cubic decimetre, 3. recommends that the name litre should not be employed to give the results of high-accuracy volume measurements. Item 2 definitely conveys the impression that, as an alternative "special" name, liter inherits the SI nature of cubic decimeter. One could, therefore, be forgiven for assuming that mL was also a fully-approved SI unit (given that prefixed occurrences of SI units are, themselves, SI units). Given its ubiquity and its usefulness, it's certainly high time CGPM gave litre (liter) the official imprimatur. Bill Potts, CMS Roseville, CA http://metric1.org [SI Navigator]     -----Original Message----- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]]On Behalf Of [EMAIL PROTECTED] Sent: Monday, October 21, 2002 12:52 To: U.S. Metric Association Subject: [USMA:22858] RE: Mishmash of units at the liquor store Joseph B. Reid wrote: >Terry Simpson wrote >>It is worse than that. It says a UK pint is 568.261 cc. >>There are two mistakes here. The conversion should be >>to ml not cc. Secondly, the UK pint is *precisely* 568 ml. >>The website is wrong. > > >The Canadian metric Practice Guide says that >1 (imperial) pint = 568.261 2 mL     Oops. Sorry, I got it wrong. Thanks for your research. The UK pint is legally defined as:   0.56826125 litre   See: http://www.hmso.gov.uk/si/si1995/Uksi_19951804_en_2.htm     Incidentally, I just realised that a 'cc' is identical to a ml. I must have known this from all my experiences with cars and motorbikes. I have only just become conscious of it.   I was instinctively reacting to the way it was written because ‘cc’ is not at all SI notation and I frequently see ‘568 ml’ as an expression. However 'cubic cm' or 'cm3' would be fine. In fact, it would be excellent since ml is not an SI unit whereas cm3 is.