64 



L. F. Nilson, 



An aly ses: 



1) 0.5192 gr. salt gave 0.215 gr selenium = 0.3021 gr. selenious acid and 

 0.2165 gr. oxide of zinc. 



2) 0.4975 gr. salt gave 0.2068 gr. selenium = 0.2906 gr. selenious acid 

 and 0.206 gr. oxide of zinc. 



In 100 parts: 



Oxide of zinc 

 Selenious acid 



found 



1. 2. 



41.70 41.41 

 58.19 58.41 



calculated 



ZnO 



SeO 2 



81 

 111 



42.19 

 57.81 



99.89 99.82 



192 100.00 



The mother-liquor of this salt, when left in the open air, deposited 

 yellow, bright, shining, four-sided crystals of the tetraselenite mentioned below. 



3. Neutral: Zn.0 2 .SeO-f 2H 2 0. 



When no diselenite, according to the next preceding experiment, 

 was to be obtained by means of heating the neutral salt with an appro- 

 priate quantity of selenious acid, I tried how it would be influenced by the 

 acid at the ordinary temperature. By adding as much anhydride as the 

 neutral salt held before, complete solution never took place, but it was not 

 long before the crystals were transformed into microscopical, foursided, 

 short, probably rhombic prisms, often combined with dome and terminal faces. 



Analyses: 



1) 0.5168 gr- salt gave 0.1797 gr. selenium = 0.2525 gr. selenious acid 

 and 0.1815 gr. oxide of zinc. 



2) 0.4077 gr. salt gave 0.1407 gr. selenium = 0.1977 gr. selenious acid 

 and 0.1445 gr. of zinc. 



Centesimally represented : 



found calculated 



1. 2. 



Oxide of zinc 35.12 35.44 ZnO 81 35.53 



Selenious acid 48.86 48.49 SeO 2 111 48.68 



Water (loss) J16^02 1^.07 2H 2 _36 15.79 



100.00 100.00 228 100.00 



Also the mother-liquor from this salt gave very beautiful and well- 

 formed crystals of tetraselenite. No diselenite of zinc is consequently to 



