Mercy Health plans to sell a hospital it has operated in Arkansas for more than a century, prompting some critics to accuse the Chesterfield-based nonprofit of abandoning its mission of serving communities in need. The decision has sparked the resignation of Mercy board member Eric Jackson and also the resignations of several board members at Mercy's affiliate, St. Joseph Mercy Health Center, in Hot Springs, Ark. Mercy has reached an agreement in principle to sell the hospital to Capella Healthcare Inc.—a private, for-profit system based in Franklin, Tenn. Plans to merge Hot Springs' two competing hospitals have jolted the city of 35,000 residents, many with family histories closely intertwined with St. Joseph's. Some fear that the merger will trigger hundreds of layoffs.