»Milk of Bismuth contains bismuth hydroxide and Bismuth Subcarbonate in suspension in water,and yields not less than 5.2percent and not more than 5.8percent (w/w)of bismuth trioxide (Bi2O3).

Mix the Bismuth Subnitrate with 60mLof Purified Water and 60mLof the Nitric Acid in a suitable container,and agitate,warming gently until solution is effected.Pour this solution,with constant stirring,into 5000mLof Purified Water containing 60mLof the Nitric Acid.Dilute 160mLof Strong Ammonia Solution with 4300mLof Purified Water in a glazed or glass vessel of at least 12,000-mLcapacity.Dissolve the Ammonium Carbonate in this solution,and then pour the bismuth solution quickly into it with constant stirring.Add sufficient 6Nammonium hydroxide,if necessary,to render the mixture distinctly alkaline,allow to stand until the precipitate has settled,then pour or siphon off the supernatant,and wash the precipitate twice with Purified Water,by decantation.Transfer the magma to a strainer of close texture,so as to provide continuous washing with Purified Water,the outlet tube being elevated to prevent the surface of the magma from becoming dry.When the washings no longer yield a pink color with phenolphthalein TS,drain the moist preparation,transfer to a graduated vessel,add sufficient Purified Water to make 1000mL,and mix.