Source: SB 5.24.17 Purport
Srila Sanatana Gosvami also states that when bell metal is treated with mercury, it can produce gold. Srila Sanatana Gosvami mentions this in regard to the initiation of low-class men to turn them into brahmanas. Sanatana Gosvami said:
yatha kancanatam yati
dvijatvam jayate nrnam
“As one can transform kamsa, or bell metal, into gold by treating it with mercury, one can also turn a lowborn man into a brahmana by initiating him properly into Vaisnava activities.” The International Society for Krishna Consciousness is trying to turn mlecchas and yavanas into real brahmanas by properly initiating them and stopping them from engaging in meat-eating, intoxication, illicit sex and gambling. One who stops these four principles of sinful activity and chants the Hare Krsna maha-mantra can certainly become a pure brahmana through the process of bona fide initiation, as suggested by Srila Sanatana Gosvami.