Complex sentence: For some time prior to 3 July 1795 he ran an apothecaries shop on Jermyn Street in partnership with one O B Smyth (or Smith), on that date, Accum left the partnership and the business was carried on by Smyth alone.
Split into simpler sentences: For some time prior to 3 July 1795 he ran an apothecaries shop on Jermyn Street in partnership with one O B Smyth (or Smith). At some point Accum left the partnership and the business was carried on by Smyth alone.