Arthashastra
एतयोर् अन्यतरस्य मूत्र लेण्द रस सिद्धं सिद्ध अर्थक तैलम् अर्क तूल पतङ्ग चूर्ण प्रतीवापं श्वेती करणम् ॥
The oil prepared from mustard seeds which have been previously kept in the urine and fluid dung of any of the two animals, a white goat and a white donkey, causes (when applied) such white colour as that of the fibre of arka plant or the down of a (white) bird.
english translation
etayor anyatarasya mUtra leNda rasa siddhaM siddha arthaka tailam arka tUla pataGga cUrNa pratIvApaM zvetI karaNam ॥
hk transliteration by Sanscript