1781 Comtesse de Moreton de Chabrillan by Louise Élisabeth Vigée Lebrun (auctioned by Heritage Auctions)
This is probably Jeanne Marie Louise de Moreton de Chabrillan who married twice.
From batguano.
This is a wonderful example of a chemise à la reine; the Dreamstress site uses it as an example of the style. It resembles later Empire style dresses, but the waist band is wider and the waistline is lower.
Keywords: 1781, Vigée Lebrun, Comtesse de Moreton, Countess, French, long high straight coiffure, ribbon headdress, feathered hat, scoop décolletage, ruffles, bows, waist band, natural waistline, floral bodice ornament, wrap, lace, chemise à la reine