Dr Joseph Priestley, 1790 (pastel on grey paper)

A framed colour drawing on grey paper, showing: a half-length portrait in profile of Dr Joseph Priestley (1733-1804), theologian and naturalist who is remembered for the identification of several gases, most notably oxygen, but also ammonia, sulphur dioxide and carbon dioxide; this work is undated, and from the apparent age of the sitter was thought to have been made about 1790; however, Priestley was in America from 1794 to 1804, where the artist was also resident for some of this time, and may therefore date to 1794-1796; the National Portrait Gallery's version of this work (object no. NPG 175) is dated to this time; for an Ellen Sharples miniature on ivory of the same sitter, see K1054