8 P. T. Cleve, 



sidering that oxygen was given off immediately after the precipitation 

 and that products of this kind are very liable to lose oxygen, one may 

 with some probability give preference to the formula RoOj. Still it is 

 a question, which cannot be answered, whether these products are really 

 peroxides and not a kind of hydrate containing H2O2, in some manner 

 analogous to the compounds of BaOa, NaoO^ etc. with H2O2, which were 

 discovered by Schöne. 



Sulphide of samarium. 



Oxide of samarium was ignited in a current of hydrogen, satu- 

 rated with vapours of bisulphide of carbon. It was blackened with 

 carbon, but its weight was yerj slightly increased, so that it may be 

 concluded that the oxide of samarium is not attacked by bisulphide of 

 carbon at a red heat. 



Fluoride of samarium 



2SmFl3 + H2 0. 



Hydrofluoric acid produces with solutions of the salts of sama- 

 rium a whitish, transparent, voluminous, and non-crystalline precipitate 

 which, on heating the solution, settles down as a heavy powder in a 

 very fine state of division. The fluoride is not soluble in dilute acids. 



I. 1.0888 gram of the fluoride, dried at 110°, gave with sulphuric 

 acid 1.5026 gram SmäSSO^. 



II. 2.0857 gram, dried at 100", gave 2.8801 gram SmgoSOi. 

 In percent: 



216 



It seems as if a little of the water were lost at 100°, as the 

 analyses of two different preparations gave one percent Sm too much. 

 This is also the case with the fluorides of the other cerium- and yttrium- 

 metals. 



