Comparison of the imperial and US customary measurement systems metre, as 1852 metres. Traditionally, both Britain and the US used three different weight systems: troy weight for precious metals, avoirdupois weight for most other purposes and apothecaries' weight for medicines. However, apothecaries' weight has now been superseded by the metric system. One important difference is the widespread use in Britain of the stone of 14 pounds () for body weight. This unit is not used in the United States, although its influence was seen in the practice, until World War II, of selling flour by a barrel of 196 pounds (14 stone). Another difference arose when Britain abolished the
Heavy metals differences become less clear at the boundaries. Light structural metals like beryllium, scandium, and titanium have some of the characteristics of heavy metals, such as higher melting points; post-transition heavy metals like zinc, cadmium, and lead have some of the characteristics of light metals, such as being relatively soft, having lower melting points, and forming mainly colourless complexes. Heavy metals are present in nearly all aspects of modern life. Iron may be the most common as it accounts for 90% of all refined metals. Platinum may be the most ubiquitous given it is said to be found in, or used