Synonym. - Ferrum Pyrophosphoricum.

This is a very useful and elegant preparation; it is readily soluble in water, keeps well, and has remarkably little styptic taste. It is the Citro-ammoniacal Pyrophosphate of the Paris Codex, and can be procured from the manufacturing chemists.

Characters. - Transparent crystalline scales, which are readily soluble in water, forming a green' solution, and should have no acid or bitter taste. The solution gives a blue precipitate with the yellow Prussiate of Potash.

Preparation. - 1 drachm of the scales may be dissolved in 8 1/2 drachms of distilled water, and then 1 drachm of rectified spirit may be added. This causes a precipitate at first, but it is re-dissolved by shaking. This constitutes lx; 1 must be made with a mixture of distilled water 3 parts, and rectified spirit 1 part; 3x with proof spirit, 2 with spirit 20° over proof, and 5x with rectified spirit.