Liter
The liter (of the Greek λίτρα will lítra , old measurement of capacity - a book of twelve ounces - equal to sixteenth of the bushel is 0,813 liter) is a measuring unit of Volume. It is defined since 1964 like a special name given to the cubic decimetre. Although apart from the international Système (IF) of units, the liter is of use with this system.
Formerly, it was defined like the volume occupied by the mass of one kilogram pure water, with its maximum of density and under the normal atmospheric pressure. This definition was repealed following the observation in 1960 of a difference with the decimetre cubes of 28 millionth.
Its origin is in the desire of unification of the measurements requested by the Constituent Assembly of 1791 vis-a-vis from the various measuring units then in progress. After having found that the Mètre is equal to the 10 millionth part of the quarter of the terrestrial meridian line, one decides to adopt a cubic measure in relation to this Mètre: it is the decimetre cubes in 1795 (law of the 18 germinal year III in Bulletins of the laws 1st series, IV quarter). The advantage that it is found there is that 1 liter of water is equivalent to a mass of 1 kilogram of water and to a volume of 1 decimetre cubic : three measurements of bases find their unification there: volume, mass, distance.
The liter is equal to 1/1000 of Cubic meter (symbol: m ³), it is this last unit which is that of volume of the international system.
Symbol
The two symbols L and L are recognized. In Unicode, the “tiny ℓ of round” (Unicode U+2113, 8467 into decimal) is the character recommended for the historical symbol; nevertheless, he is not recognized by BIPM. Generally, the use wants that a capital letter is used only with the symbol of a unit resulting from a proper name; tiny if not (what is thus the theoretical case of the liter). In spite of this principle, the figure 1 and the small letter L are seldom distinguished, if not badly distinguished, in the typed writings. Several countries took the practice to use the capital L. The 16 {{E}} conference of the weights and measures thus, exceptionally, vis-a-vis the practice met, retained the two symbols for this derived unit. The capital letter L is used in practice, but tiny the ℓ remains preferred by the purists (by distinguishing it well from figure 1). There is indeed no true technical reason for this exception since it is possible to use better font faces. On the ethical level, it would be with the font faces not to use the same representation for two different symbols (figure “1” and letter “it). This discussion thus gives place to many debates. In 1990, this same Office of the Weights and measures judged still premature to eliminate one from the two symbols. Certain countries (as the Canada) advise to use the tiny one each time possible: ℓ or L by defect (as long as there is no possible confusion with figure 1). The capital letter L if not (if there is risk of confusion).- 1 ℓ = 1 DM = 10 -3 m {{3}}.
Conversion
Anecdote
Wine measured with pint (0,93 ℓ), one has immediately noticed that easiest to measure a quantity of wine became to weigh it, which is made still nowadays, with the retail sale. From where the name of the liter of wine by the rabble: a kil' of red: one kilo of red wine for 1 liter of wine.
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