The sitter may be Henriette Louise de Saint Pol who became Marquise de Chamillard in 1810.
From elogedelart.canalblog.com/archives/2011/01/14/20127134.html.
This is a simple dress with a high waistline and quarter length full sleeves. It is adorned with a lace ruff.
Keywords: 1810, Massot, Marquise de Chamillard, Marquise, curly coiffure, square neckline, lace neckline ruff, quarter length full sleeves, cuffs, Empire waistline, close skirt, shoes, wrap