First Edition from 1826 Describes the engraving technique that involves applying niello, a black metallic sulfide used as a filler in metal marquetry. This rare work on the niello technique was the first written essay on this subject. Jean Duchesne Ainé (1779-1855) was a French draftsman and engraver, curator of the Print Room of the National Library, art historian, and Freemason. With original leather and board cover, with gilt lettering and embellishments. Marbled effect on board is in good condition but leather additions are worn and peeling in places. In particular, pieces are missing from the spine, which has likely been repaired at some point. A number has been sellotaped to the spine. A further number and antique dealers stamp have been added to the inside cover. Inside covers with marbling effect are in very good condition. The pages show age-normal foxing. There is a very faint pencil inscription on the title page and some notes have been added to margins in pencils. Engra