Ammonium Dihydrogen Phosphate from Superphosphate: Lagrange's Process

Monoammonium phosphate from superphosphate, by Lagrange's process (Thorpe, 1912). Water and steam wash the soluble phosphate out of the superphosphate. A little barium carbonate takes out the gypsum still dissolved, and ammonia in slight excess throws down the last of the lime. The clear liquor holds the salt. The picture: our own drawing.