Litre

The litre (International spelling) or liter (American spelling) (SI symbols L or l, commonly, but incorrectly, abbreviated as ltr) is an SI accepted metric system unit of volume equal to 1 cubic decimetre (dm³), 1,000 cubic centimetres (cm³) or 1/1,000 cubic metre. A cubic decimetre (or litre) occupies a volume of 10×10×10 centimetres (see figure) and is thus equal to one-thousandth of a cubic metre.

The original French metric system used the litre as a base unit. The word litre is derived from an older French unit, the litron, whose name came from Greek - where, perversely, it was a unit of weight, not volume - via Latin, and which equalled approximately 0.831 litres. The litre was also used in several subsequent versions of the metric system and is accepted for use with the SI, although not an official SI unit—the SI unit of volume is the cubic metre (m³). The spelling used by the International Bureau of Weights and Measures is "litre", a spelling which is shared by almost all English-speaking countries. The less common spelling of "liter" is more predominantly used in American English.

Two-liter bottle

The two-liter bottle is a common container for soft drinks. These bottles are produced from polyethylene terephthalate, also known as PET plastic, using the blow molding process. Bottle labels consist of a printed, tight-fitted plastic sleeve. A resealable screw-top allows the contents to be used at various times while retaining carbonation.

In the United States, the two liter bottle is one of the few cases where a product is sold by a round number of metric units. Since very few other beverages are sold in this exact quantity, the term "two-liter" in American English almost invariably refers to a soft drink bottle. Other common metric sizes for plastic soft drink bottles include 500 milliliters, 1 liter and 3 liters.

In many Eastern European countries such as Russia or Slovakia, plastic bottles are used for selling beer as well.

History

PepsiCo introduced the first two-liter sized soft drink bottle in 1970. The bottle was invented by a team led by Nathaniel Wyeth of DuPont who received the patent in 1973. In 1985, a three-liter bottle appeared on supermarket shelves. The design is still used to this day by some bottlers. Most modern-day two-liter bottles are one piece of PET (Polyethylene terephthalate) with a base that is molded with a radial corrugation to provide strength for the bottom and the ability to stand upright. Most early two-liters had a separate opaque base glued to the hemispherical bottom of the clear PET flask. This base had a coaxial corrugation and drain holes. It was abolished in the 1990s, in part due to difficulties recycling the two separate plastics.