Barium nitroprusside, Ba[Fe(CN)₅NO].3H₂O

Barium nitroprusside, Ba[Fe(CN)₅NO].3H₂O, is prepared by precipitating a solution of the sodium salt with zinc sulphate and boiling the zinc salt thus obtained with a suspension of precipitated barium carbonate. The filtered solution of the barium salt is evaporated under reduced pressure, and the salt crystallised from alcohol.