March 26, 1776. South Carolina adopted a temporary constitution to regulate its internal affairs until, in the words of the preamble, "an accommodation of the unhappy differences between Great Britain and America can be obtained (an event which though traduced and treated as Rebels we still earnestly desire.)"

The Second Provincial Congress then adjourned to five o’clock the same afternoon, when it reconvened as the South Carolina General Assembly. Two days later, the constitution was publicly read from the Exchange Building, and John Rutledge was proclaimed as president of the colony, amid the shouts of spectators and cannon salutes from the artillery and the provincial ships in the harbor.

-- Lipscomb, Terry W. South Carolina Becomes a State
--The Road from Colony to Independence--1765-1776
Columbia, South Carolina: South Carolina Department of Archives and History, 1976

Sunday May 17, 1780 during the terrific siege of Charleston by the British, General William Moultrie placed his magazine of powder in the Exchange (one authority estimated the amount of powder at ten thousand pounds, another at one hundred thousand pounds.) After the evacuation of Charleston by the British, General Moultrie returned to the City and to his great amazement, found his powder magazine intact.

This large amount of powder was stored in the North East corner of the basement of the building. The doors and windows were then "bricked up." When the British finally captured the City, the apartment next to the powder magazine was used as a "Provost" for the incarceration of persons under suspicion.