36 



L. P. NlLSON, 



Analyses: 



1) 0.5327 gr. salt when analyzed in the same manner as in the preceding- 

 case gave, 0.2246 gr. sulphate of calcium = 0.0925 gr. lime and 0.2672 

 gr. selenium or 0.376 gr. selenious acid. 



2) 0.58 gr. salt gave likewise 0.2465 gr. sulphate of calcium =0.1015 gr. 

 lime and 0.2892 gr. selenium or 0.4063 gr. selenious acid. 



Centesimally represented : 



experiment theory 



1. 2. 



Lime 17.36 17.50 CaO 56 17.83 



Selenious acid 70.59 70.06 2Se0 2 222 70.70 



Water (loss) 12.05 12.44 2H 2 36 11.47 



100.00 100.00 314 100.00 



3. Diselenitc: 2[Ca.0 2 .SeO + Se0 2 ] + H 2 0. 



When to 1 molecule of the preceding salt 2 molecules of selenious 

 acid were added — by which it was intended to ascertain whether any 

 tetraselenite were formed — the solution, allowed slowly to evaporate, at 

 about 60°, in a low vessel covered with a glass-plate, afforded a salt in 

 very large, short crystals in form of irregularly six-sided lamels; possibly 

 they are formed by a rhombic prism with macrodiogonal dome- and end- 

 faces. The salt, permanent in the air, is very soluble in water. 



Analyses: 



1) 0.522 gr. salt, treated in the above manner, gave 0.2405 gr. s'ulphate 

 of calcium = 0.099 gr. lime and 0.2847 gr. selenium or 0.4 gr. sele- 

 nious acid. 



2) 0.5712 gr. salt gave 0.2645 gr. sulphate of calcium = 0.1089 gr. lime 

 and 0.3136 gr. selenium or 0.4406 gr. selenious acid. 



3) 0.5765 gr. salt, after fuming with sulphuric acid and heating, gave 0.281 

 gr. sulphate of calcium or . 1 157 gr. lime. 



Calculated on 100 parts: 



experiment theory 



1. 2. 3. 



Lime 18.97 19.06 20.07 2CaO 112 19.51 



Selenious acid. . . 76.63 77.14 — 4Se0 2 444 77.35 



Water (loss) .... 4.40 3.80 — H 2 18 3.14 



100.00 100.00 ^574 100.00 



