By (late) Sohrabji H. Kutar, U. K. (1969)
Nirang is obtained from the consecrated varasyaa and from other bulls maintained on a hygienic diet. The vessels which receive the bulls’ urine are not only thoroughly scoured, but are themselves purified and consecrated; and the liquid is then sanctified for holy purposes, through the long, intricate, complex and exalted ritual ceremony and prayer service of the Nirangdin. Thereafter imbued by these prayers and blessings, it becomes an agent of purification. These are the tenets of traditional Zoroastrian observance and belief; but in this scientific age it seemed desirable to reinforce them with scientific proof.
Courtesy : Hushang Vakil