Claude Émile Jean-Baptiste Litre
Template:Short description Template:Use dmy dates Claude Émile Jean-Baptiste Litre (1716–1778) is a fictional character created in 1978 by Kenneth Woolner of the University of Waterloo to justify the use of a capital L to denote litres.
The International System of Units usually only permits the use of a capital letter when a unit is named after a person.<ref name=BIPM>{{#invoke:citation/CS1|citation |CitationClass=web }}</ref> The lower-case character l might be difficult to distinguish from the upper-case character I or the digit 1 in certain fonts and styles, and therefore both the lower-case (l) and the upper-case (L) are allowed as the symbol for litre. The United States National Institute of Standards and Technology now recommends the use of the uppercase letter L,<ref>Non-SI units accepted for use with the SI by the CIPM – NIST.</ref> a practice that is also widely followed in Canada and Australia.Template:Citation needed
Woolner perpetrated the April Fools' Day hoax in the April 1978 issue of "CHEM 13 News", a newsletter concerned with chemistry for school teachers. According to the hoax, Claude Litre was born on 12 February 1716, the son of a manufacturer of wine bottles. During Litre's extremely distinguished fictional scientific career, he purportedly proposed a unit of volume measurement that was incorporated into the International System of Units after his death in 1778.<ref name=":0">{{#invoke:citation/CS1|citation |CitationClass=web }}</ref><ref>{{#invoke:citation/CS1|citation |CitationClass=web }}</ref>
The hoax was mistakenly printed as fact in the IUPAC journal Chemistry International and subsequently retracted.<ref name=":0" /><ref>Template:Cite magazine</ref> In reality, the litre derives its name from the litron, an old French unit of dry volume.