22 



409.1 



The composition agrees perfectly with that of the corresponding 

 salt of samarium. In my paper on didymium of 1874') I arrived on 

 calculation at the same formula, but with only 2H2O. The salt then 

 analysed was dried over oil of vitriol and had lost 4H2O. 



Nitro-oxalate of didymium 



^' C,0,H 



C3O4 +IIH2O 

 Di ) C,0,H 



' NO, 



A solution of oxalate of didymium in nitric acid deposits by 

 slow evaporation over caustic potash at the ordinary temperature beau- 

 tiful, brillant and transparaut, red crystals, sometimes of considerable 

 size (2 — 3 centimetres). The salt is unstable and emits in the air nitric 

 acid. It is also decomposed by pure water. 



I. a. 0.7856 gram left on ignition 0.3075 gram' DisOj. 



b. 0.4950 gram was decomposed with ferrous chloride and hy- 

 hydrochloric acid, and gave 25.2 cub. cent. NO of the t° 17°.5 and under 

 the barometric pressure of 750 m.m. 



c. 0.6563 gram was burnt with oxide of copper and the nitro- 

 gen determined as usual by the Dumas method. 17.6 cub. cent, nitrogen, 

 t" 17", barometric pressure 750 m.m., were thus obtained. 



d. 1.0215 gram was burnt with Chromate of lead and gave 0.2519 

 gram H2O and 0.3169 gram CO2. 



') Bihang till K. Sv. Vet. Akad. Handlingar II, X:o 8, p. 20. 



