The normal ortho-phosphate, Pb3(P04)2, is a white precipitate obtained by adding sodium phosphate to lead acetate; the acid phosphate, PbHPO 4, is produced by precipitating a boiling solution of lead nitrate with phosphoric acid; the pyrophosphate and meta-phosphate are similar white precipitates.
Crystals may be obtained by heating di-calcium pyrophosphate, Ca2P207, with water under pressure.
The same reaction is made use of in the quantitative determination of magnesium, the white precipitate of magnesium ammonium phosphate being converted by ignition into magnesium pyrophosphate and weighed as such.
On heating they yield phosphine and leave a residue of pyrophosphate, or a mixture of metaand pyrophosphates, with a little phosphorus.
The metallic phosphites are stable both dry and in solution; when strongly heated they evolve hydrogen and yield a pyrophosphate, or, especially with the heavy metals, they give hydrogen and a mixture of phosphide and pyrophosphate.