SB 11.21.12

dhānya-dārv-asthi-tantūnāṁ
 rasa-taijasa-carmaṇām
kāla-vāyv-agni-mṛt-toyaiḥ
 pārthivānāṁ yutāyutaiḥ
Synonyms: 
dhānya — of grains; dāru — of wood (in the form of both ordinary objects and sacred utensils); asthi — bone (such as elephant tusks); tantūnām — and thread; rasa — of liquids (oil, ghee, etc); taijasa — fiery objects (gold, etc); carmaṇām — and skins; kāla — by time; vāyu — by air; agni — by fire; mṛt — by earth; toyaiḥ — and by water; pārthivānām — (also) of earthen objects (such as chariot wheels, mud, pots, bricks, etc); yuta — in combination; ayutaiḥ — or separately.
Translation: 
Various objects such as grains, wooden utensils, things made of bone, thread, liquids, objects derived from fire, skins and earthy objects are all purified by time, by the wind, by fire, by earth and by water, either separately or in combination.
Purport: 

The word kāla, or “time,” is mentioned here, since all purificatory processes take place within time.