The words of the LORD are pure words: as silver tried in a furnace of earth, purified seven times. The words of the Lord are pure words - None of his promises shall fall to the ground; the salvation which he has promised shall be communicated.
Silver tried in a furnace of earth - A refer ence to the purification of silver by the cupel. This is a sort of instrument used in the purification of silver. It may be formed out of a strong iron ring or hoop, adjusted in width and depth to the quantum of silver to be purified, and rammed full of well pulverized calcined bone. The metal to be purified must be mingled with lead, and laid on the cupel, and exposed to a strong heat in an air furnace. The impurities of the metal will be partly absorbed, and partly thrown off in fume. The metal will continue in a state of agitation till all the impurities are thrown off; it will then become perfectly still, no more motion appearing, which is the token that the process is completed, or, according to the words of the text, is seven times, that is, perfectly purified.