And he shall sit as a refiner and purifier of silver: and he shall purify the sons of Levi, and purge them as gold and silver…
The following description of silver refining is given by Napier: — "When the alloy is melted upon a cuppel and the air blown upon it, the surface of the melted metals has a deep orange-colour with a kind of flickering wave constantly passing over the surface, caused by the combining of the oxygen with the impurity; and these being blown off as the process proceeds, the heal is increased, because the nearer purity the more heat is necessary to keep it in fusion; and in a little the colour of the fused metal becomes lighter, the impurities only forming reddish striae which continue to pass over the surface. At this stage the refiner watches the operation, either standing or sitting, with the greatest earnestness, until all the orange colour and shading disappears, and the metal has the appearance of a highly-polished mirror, reflecting every object around it, even the refiner, as he looks upon the mass of metal, may see himself as in a looking-glass, and thus he can form a very correct judgment respecting the purity of the metal If he is satisfied the fire is drawn, and the metal removed from the furnace; but if not considered pure more lead is added and the process is repeated." All this is illustrative of the dealings of God with the Christian, who, being put into the furnace of affliction, is often kept there for a considerable time, the heat meanwhile increasing daily; but no sooner is the end answered, and the drop of sin removed, than he is taken out of the furnace reflecting the image of his Lord.
Parallel VersesKJV: And he shall sit as a refiner and purifier of silver: and he shall purify the sons of Levi, and purge them as gold and silver, that they may offer unto the LORD an offering in righteousness.