Lewis acids and bases studied chemical bonding. In 1923, Lewis wrote "An acid substance is one which can employ an electron lone pair from another molecule in completing the stable group of one of its own atoms." The Brønsted–Lowry acid–base theory was published in the same year. The two theories are distinct but complementary. A Lewis base is also a Brønsted–Lowry base, but a Lewis acid doesn't need to be a Brønsted–Lowry acid. The classification into hard and soft acids and bases (HSAB theory) followed in 1963. The strength of Lewis acid-base interactions, as measured by the standard enthalpy of formation of an adduct
CSX milepost prefixes Also, like the ACL, the SAL mainline ran from Richmond, Virginia to Tampa, Florida. The S Line is today discontinuous and segments of the original line have been abandoned (notable abandoned segments are between Chester, Virginia and Norlina, North Carolina, and between Riceboro and Seals, Georgia. The Seaboard main line from Richmond to Tampa, heart of its 2600-mile system in 1900, had been built by the following companies: CSX milepost prefixes Most CSX railroad lines are given lettered prefixes before milepost numbers. These prefixes are one to three letters long with the first letter usually refer to the former company.