I will turn my hand upon thee. — The phrase, like the English “visit,” presents both a severe and a gracious aspect. Of the former we have instances in Psalms 81:14; Amos 1:8; of the latter in Zechariah 13:7. The context here inclines to the latter meaning. Jehovah punishes that He may save, and smites that He may heal.
Purely purge away thy dross. — Better, will smelt away thy dross with lye, or potash, which was used in the smelting process. The imagery of Isaiah 1:22 is resumed. The great Refiner can purify the debased metal. In Malachi 3:2-3, we have the same image expanded. The process involved, of course, the rejection of the dross — i.e., in the interpretation of the parable, of the lead that would not let itself be turned to silver.
Tin. — Better, perhaps, lead. In either case Isaiah’s knowledge of metallurgy was probably due to intercourse with the Phœnicians, who brought both lead and tin from Tarshish (i.e., Spain).