422 Berzelius on a new Mineral Body, [Dec. 



that the melted salt runs out. This property, which the sele- 

 niate of lime has in common with the seleniates of magnesia 

 and of manganese, is very remarkable. I do not pretend to 

 explain it. 



The biseleniate is obtained when the preceding salt is dissolved 

 in selenic acid. The solution crystallizes to the last drop in the 

 form of small prisms, which are not altered by exposure to the 

 air. Caustic ammonia removes one half of the acid, and leaves 

 the neutral salt. Heat produces the same effect. 



7. Seleniate of Magnesia. — Selenic acid decomposes the 

 carbonate of magnesia with effervescence without however dis- 

 solving it, because the new compound is very little soluble. The 

 result is a crystalline powder. It is soluble in boiling water, but 

 a great quantity of that liquid is requisite. The solution when 

 evaporated gives small crystalline grains, which under the 

 microscope exhibit the form of small prisms, and small four- 

 sided tables. When heated, the salt gives out its water of 

 combination, and becomes enamel-white. Heat does not melt 

 it, nor drive off its acid; but it attacks the glass vessel, which 

 swells up, and is penetrated by a great number of bubbles. 



We obtain the biseleniate by dissolving the preceding salt in 

 selenic acid and adding alcohol to the solution. The biseleniate 

 precipitates in a pulpy coherent mass, which attracts moisture 

 from the air, and which does not crystallize though it be 

 dissolved in water and the solution evaporated. 



8. Seleniate of Alumina. — The. neutral salt is insoluble. We 

 obtain it by evaporating a solution of muriate of alumina to 

 dryness, dissolving the salt in water, and precipitating it by 

 biseleniate of ammonia. The solution of alum is not precipitated ; 

 but if we mix with it a neutral seleniate with an alkaline base, 

 the seleniate of alumina is precipitated. The precipitate is a 

 white powder, which, when heated, gives out in the first place 

 water, and afterwards the whole of its acid. 



The biseleniate is produced by dissolving the preceding salt, 

 or the hydrate of alumina in selenic acid. The liquid has an 

 astringent taste, and, when evaporated, yields a colourless, trans- 

 parent mass, similar to gum. 



9. Seleniate of Glucina. — The neutral salt is a white insoluble 

 powder. The biseleniate is soluble. When evaporated, it leaves 

 a mass resembling gum. Both salts lose their acid when heated. 



10. Seleniate of Yttria. — The seleniates with an alkaline base, 

 when dropped into a solution of yttria, throw down large white 

 flocks, which do not dissolve in an excess of selenic acid. 

 When dried, the salt has the form of a white powder, which, 

 when heated, lets go first its water, and then its acid. 



11. Seleniate of Zirconia. — This salt is a white powder, inso- 

 luble both in water and in selenic acid. Heat decomposes it. 



12. Seleniate of Zinc. — The neutral saltis a crystalline powder, 

 Insoluble in water. When heated, it first gives out its water of 



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