DiDYMIÜM. 15 



Anhydrous salt: DijSSeOi. 

 Spec. Grav: 



1.7907 gram, i" 12''.5 sp. Gr. 4.416 



1.4309 



1.1772 

 1..3935 



» » » 4.430 



t" 18° » » 4.461 



» » » 4.460 



Mean of the four determinations: 4.442. 

 Mol. vol.: 160.5. 



Selenate of didymium and potassium 



DiK2Se04+5H20. 



By evaporating the mixed solutions of the simple salts at the 

 ordinary temperature (about 17°) large and well formed red prisms, 

 easily soluble in water are obtained. The salt loses at 100° 14.16 per- 

 cent H2O, or 4 '/2 mol. (cal. 14. 50). 



0.4410 gram was boiled with HCl and precipitated with SOg. The 

 precipitated selenium weighed 0.1237 gram. The filtrate was evaporated 

 and precipitated with ammonia, and the didymium-hydroxide redissolved 

 and precipitated with oxalic acid. From the filtrate from the hydroxide 

 0.1977 gram KgPtCle was obtained. The oxalate of didymium left on 

 ignition 0.1308 gram DigOa. 



0.4316 gram gave in the same manner 0.1204 gram Se, 0.1278 

 gram DigOj and 0.1997 gram KgPtCle. 



In percent: 



Di,03 . . . 



K^O ... 



SeOs . . . 



fl,0 . .'. 



c ale 



100.00 100.00 557.1 100.00 



Spec. Grav: 



0.5877 gram, large crystals, t.° 13" sp. Gr. 3.174 

 0.6795 » » » » » » » 3.178 



