To test whether the surface of furniture is french-polished or cellulose-lacquered (the two basic types of furniture finishes), rub an inconspicuous area of the surface with a cloth dipped in methylated spirit. Within a few minutes. As the polish is dissolved by the spirit, a french-polished surface becomes soft and leaves a stain on a finger rubbed across the area. Whereas a cellulose finish is not affected by the spirit.
Alternatively, scrape the surface with a sharp knife. French polish will come away from the surface in small shavings that crumble to a brown dust: cellulose produces a white dust.