Arthashastra
शकुन कण्गु तैल युक्ता हरि ताल मनः शिलाः श्यामी करणम् ॥
Sulphuret of arsenic and red arsenic mixed with the oil extracted from sakuna (a kind of bird) and kanka (a vulture) causes blackness.
english translation
zakuna kaNgu taila yuktA hari tAla manaH zilAH zyAmI karaNam ॥
hk transliteration by Sanscript