Samarium. 7 



dilute sulphuric acid the unoxidised excess of the ferrous salt was esti- 

 mated by permauganate of potash. Afterwards the samarium was deter- 

 mined 'in the liquid by precipitation with oxahc acid, ignition of the 

 oxalate and reprecipitation as oxalate. 



The experiment gave: 

 0.781S gram Sm.Oa and 0.0513 gram 0, or for 100 SniaOs 6.56 0. 



This corresponds pretty nearly to 



Sm.Os 



which requires for 100 SmgOj 6.90 oxygen. 



If the precipitate be dried over sulphuric acid, it forms semi-trans- 

 parent yellowish pieces, which were powdered several times. Afterwards 

 it was analysed. 



0,772 gram was heated with bichromate of potash in a current 

 of dry air and gave 0.0178 gram CO2 and O.118O gram H2O. 

 0.7241 gram gave by ignition 0.5581 gram SnigOg. 



0.7542 gram was mixed with 3.1386 gram (NH4)3Fe2S04 + 6H0O , 

 and warer, sulphuric acid was added (when a great number of small 

 gasbubbles escaped) and afterwards, 23.3 c.c. permangante of potash 

 (100 c.c. = 0.939 Fe) were required to oxidise the excess of ferrous salt. 



In percent: Ratio 



SmaOs 77.07 1 



4.35 1.23 



CO. 2.31 0.24 



H2Ô 15.28 3.83 



99.01 



The drv substance analysed, which had been obtained from the nitrate 

 of samarium, contained also a trace of nitric acid. 



On comparing the ratio between SmjOj and in the moist and 

 in the dry product, it will be seen that comparatively- little oxygen 

 was lost in drying. 



I have examined the composition of the products formed hj the 

 action of peroxide of hydrogen upon the h3^droxyde of the other earths') 

 and have found that didymium, lanthanum, j^ttrium and erbium all give 

 products of perfectly analogous composition, or agreeing with the ge- 

 neral formula R4O9, when recently washed and in a moist state. Con-^ 



•) Bull. Soc. Chiin. XLIII, p. 53, 1885. 



