The simplest formulae which correspond to this composition are: 



SmPO, + 2H,0 SmPO, +H,0 



Sm^Og 174 61.92 174 66.16 



P^Og 71 25.27 71 27.00 



H,0 ... . . 36 12.81 18 6.84 



281 100.00 263 lOO.oo 



The dififerences between the numbres found by analysis and those 

 calculated from the formulae are considerable, but one could not expect 

 better from a substance such as the amorphous phosphate, the compo- 

 sition of which may vary. In any case the composition indicates that 

 the precipitate which di-sodium-orthophosphate gives with salts of sa- 

 marium is principally composed of trimetallic phosphate. 



Pyrophosphate of samarium 



Sm 

 H 



|0„P,03 + 3V,H,0. 



Pyrophosphoric acid easily dissolves the hydrate of samarium, 

 and the solution deposits after some time, on spontaneous evaporation, 

 small compact granules of densely crowded crystals. The salt loses at 

 100° 10.79 percent H^O, corresponding to 2 mol. HjO (calc. 9.28 percent). 



0.4456 gram salt, pressed between filter-paper, lost on ignition 

 0.0800 gram H^O. 



0.4118 gram was dissolved in nitric acid, and the solution boiled. 

 On adding oxalic acid 0.1852 gram Sm^Oj was thrown down as oxalate. 

 From the filtrate 0.2348 gram MggPjO, was obtained. 



