110 



L. F. Nilson, 



Calculated on 100 parts: 



experiment theory 



1. 2. 3. 4. 



Oxide of bismuth 50.86 50.99 — — Bi 2 3 468 50.32 



Selenious acid . . — — 46.83 47.02 4Se0 2 444 47.74 



H 2 18 1.94 



930 100.00 



Bismuth seems incapable of uniting with selenious acid to any salt, 

 more acid than the above-mentioned: for being-, under the same circum- 

 stances that have been often described in the preceding, digested with 2 

 and 8 mol. selenious acid, it remained unaltered, crystallized in small prisms, 

 when the selenious acid had been dissolved out with water. The analyses 

 1 — 3 refer to a material, obtained when a diselenite, 4 — 6, when a tetra- 

 selenite might have been formed. 



Analyses: 



1) 0.6035 gr. salt, heated to whiteness, gave 0.3085 gr. oxide of bismuth. 



2) 0.5812 gr. salt gave 0.196 gr. selenium or 0.2754 gr. selenious acid. 



3) 0.502 gr. salt gave 1685 gr. selenium or 0.2367 gr. selenious acid. 



4) 1.093 gr. salt, heated to whiteness, gave 0.54 gr. oxide of bismuth. 



5) 0.5035 gr. salt gave 0.1725 gr. selenium or 0.2423 gr. selenious acid. 



6) 0.505 gr. salt gave 0.174 gr. selenium or 0.2445 gr. selenious acid. 



Calculated on 100 parts: 



1. 2. 3. 4. 5. 6. 

 Oxide of bismuth ... 51.12 — — 49.41 — — 

 Selenious acid — 47.40 47.15 — 48.12 48.41, 



values, closely agreeing with those, calculated from the formula above. 



This salt, suffering no change at 100°, shows a composition, ana- 

 logous to that of the selenites that have been found above to be so charac- 

 teristic for the sexivalent metals, but unlike them, contains no water of 

 crystallization. Now, bismuth being unquestionably trivalent, such a cir- 

 cumstance might possibly seem to plead for the trivalence of the rare 

 earth-metals, in opposition to what has been stated above. It suffices, 

 however, to remark how far bismuth in its properties differs from these 

 elements, and how much these latter resemble the undoubtedly sexivalent 

 Fe 2 , Al 2 , Cr 2 , in order to remove every doubt, which, owing to the said 

 correspondence in this single selenite, might have been raised of the 



