2765.8 



13 



Sulphate of didymium and ammonium 



DiNH4 2SO, + 4H,0. 



From the mixed solutions of the simple salts small red crystals 

 are obtained. These crystals are soluble with difficulty and are not alte- 

 red by exposure to the air. They lose SHgO at 100" (found 12.47 per- 

 cent, calc 12.73). 



0.5095 gram lost by heating to 220" 0.0937 gram HgO and gave 

 0.3799 gram Di23S04. 



0.864 gram gave 0.3408 gram DiäOs and 0.937 gram BaSO<^. 



0.836 gram gave 0.335 gram DijOs and 0.908 gram BaSO^. 



In percent: ^ , 



^ Calc 



Di^Oa 39.41 39.44 40.07 166 39.15 



(NH,),0 — — — 26 - 



SO3 — 37.24 37.29 160 37.74 



H2O ..... 16.75 — — 72 16.98 



424 

 Spec. Grav: 



I. Crystallised salt, small crystals 



0.8296 gram, t° 15, sp. gr. 2.575 

 1.1825 » » )) » 2.575 



Molecular volume: 164.7. 



II. Anhydrous salt. 



1.3008 gram, t° 15" sp. gr. 3.086 

 1.0362 » » » » 3.075 



