28 P. T. Cleve, 



Crystalline form monosymmetric. Crystals protracted parallel to 

 the orthodiagonale. 



a : b : c = 1.32544 : 1 : 1.0642 



/5=76'' 53' 



Planes: ooP; ooPoo; + Poo; — Poo; oP. (C.Morton). 



Ethylsulphate of didytnium 



Di3C2H5,3SO,-f-9H20. 



This compound was obtained by double decomposition of the 

 ethylsulphate of barium and the sulphate of didymium. The salt cry- 

 stallises well in large light-red crystals. It loses 33.24 percent water 

 and alcohol at 100". 



0.4386 gram gave 0.1861 gram DigSSOi. 



1.0744 » » t" 18" » » 1.867 



Mean of both determinations: 1.86.3. 

 Molecular volume: 364.5. 



Crystalline form hexagonal. Optical negative, splendid crystals, 

 protracted parallel to one of the horizontal axes of ooP and capped by 

 a plane of ooP, parallel to the axis. 



a : c = 1 : 0.50843. 



Planes: ooP; ooP2; 2P2; P; 2P2. (C.Morton). 



