Fine brass. This may stand as a translation of χαλκολίβανος, a word which occurs here and in Revelation 2:18 only, and the second half of which has never been satisfactorily explained. It may have been a local technical term in use among the metalworkers of Ephesus (Acts 19:24; 2 Timothy 4:14).
The Rhemish Version renders it "latten." In what follows, the Revised Version is to be preferred: "as if it had been refined in a furnace; and his voice as the voice of many waters." It is tempting to think that "the roar of the sea is in the ears of the lonely man in Patmos;" but the image seems rather to be that of the sound of many cataracts (comp.
Ezekiel 1:24; Ezekiel 43:2; Daniel 10:6). There is singularly little of the scenery of Patmos in the Apocalypse.