To darken a Spanish mahogany picture frame, dissolve loz. of bichromate of potash in 1 pt. of warm water. Apply the solution with a sponge or brush, getting it well into all quirks or hollows; wipe off any surplus with rag. Several coats may be given till the desired tone is gained. "When dry, wipe over with raw linseed oil; smooth down by well rubbing with coarse rag or finest-grade glasspaper. The work may be finished with French or wax polish.