Bismuth Oxide: Subnitrate Boiled with Sodium Hydroxide Solution (British Pharmacopoeia, 1907)

Boil bismuth subnitrate with sodium hydroxide solution: bismuth hydroxide falls and sodium nitrate stays dissolved. At 100 °C the hydroxide loses its water, leaving bismuth oxide, a dull lemon-yellow powder. Source: The Dispensatory of the United States of America (1907), Bismuthi Oxidum, after the British Pharmacopoeia. Not given: amounts, strength or time; those are stated as not given. The 10 % lye, washing and filter are ours. Picture drawn by Youblob.