Preparation of Bismuth Subsalicylate from Bismuth Subnitrate

It was shown that bismuth subsalicylate BiC₇H₅O₄ of high purity (with low contents of impurity metals and nitrate ions) is advisable to obtain from bismuth subnitrate [Bi₆O₅(OH)₃](NO₃)₅⋅3H₂O through converting it into oxide Bi₂O₃ by treating with a solution of sodium hydroxide and then into bismuth subsalicylate BiC₇H₅O₄ by treating bismuth oxide with a lactic acid–salicylic acid solution at a temperature of 60–85°C.