32 



L. F. Nilson, 



The salt, being completely permanent on exposure to the air, parts 

 with half its water of crystallization at 100°. 



2. Diselenite: LiH.0 2 .SeO. 



This compound crystallizes from a strongly concentrated solution in 

 laminar, probably rhombic prisms with predominant brachydiagonal end-faces 

 and dome. The crystalline form reminds very much of that of arragonite, 

 and agrees with it even in the circumstance, that twin-iormation seems to 

 be rather common. The salt is permanent both in ordinary and dry air 

 and dissolves readily in cold water. 



Analyses: 



1) 0.6965 gr- salt gave 0.4075 gr. selenium or 0.5725 gr. selenious acid 

 and 0.2778 gr. sulphate of lithium or 0.0758 gr. lithia. 



2) 0.689 gr. salt gave 0.4032 gr. selenium or 0.5665 gr. selenious acid 

 and 0.273 gr. sulphate of lithium or 0.0745 gr. lithia. 



3) 0.3737 gr. salt, when kept over sulphuric acid, presented no change of 

 weight; but lost 0.0257 gr., when heated to 100°. 



Calculated on 100 parts: 



experiment theory 



1. 2. 3. 



Lithia 10.88 10.81 — V 2 Li 2 15 11. ll 



Selenious acid. . . 82.21 82.21 - SeO 2 111 82.22 



Water (loss). . . . 6.9 1 _6 : 98 6.88 V 2 H 2 __9 6.67 



100.00 100.00 135 100.00 



Consequently, the compound, at 100°, changes into an anhydrous 

 salt Li 2 .0 2 .SeO. -f SeO 2 , under loss of water, and without fusing at this 

 temperature; the change, however, takes place but slowly. 



3. Tetraselenite: LiH.0 2 .SeO + H 2 .0 2 .SeO. 



As is the case with the corresponding selenites of the two common 

 alkaline metals, this salt also crystallizes more easily, than both the neutral 

 salt and the diselenite. The crystals are long, four-sided prisms, with obli- 

 quely truncated ends. They are permanent even in dry air, but fuse at 

 100° and give off water. 



