Areas of Surfaces

1 The angstrom is basically defined as 10-10 meter. 2 There is a variety of “ barells” established by low or usage. For example, federal taxes on fermented liquors are based on a barrel of 31 gallons; many state laws fix the “barrel for liquids” at 31 ½ gallons; one state fixes a 36-gallon barrel for cistern measurement; federal law recognizes a 40- gallon barrel for “ proof spirits”; by custom, 42 gallons comprise a barrel of crude oil or petroleum products for statistical purposes, and this equivalent is recognized “ for liquids” by four states. 3 Frequently recognized as 1 ¼ bushels, struck measure. 11 Used in assaying. The assay on bears the same relation to the milligram that a ton of 2,000 pounds, avoirdupois bears to the ounce troy; hence the weight in milligrams of precious metal obtained from one assay ton of ore gives directly the number of troy ounce to the net ton. 12 The gross or long ton and hundredweight are used commercially in the United States to only a limited extent, usually in restricted industrial fields. These units are the same as the British “ton” and “hundredweight”.