Intelligence and Miscellaneous Articles. 413 



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retted hydrogen gas passed over it, it becomes slightly gray, but no 

 trace of water is perceptible. Pelopic and niobic acids are converted 

 by the same treatment slowly but entirely into sulphurets, with for- 

 mation of water and separation of sulphur. 



Metallic pelopium can be prepared from the chloride by treat- 

 ment with ammonia, in the same way as the metals from the chlo- 

 ride of tantalium and chloride of niobium. It has the greatest re- 

 semblance to tantalium. 



When the ignited acids, which are insoluble in almost all reagents 

 in the moist way, are fused in a silver crucible with hydrate of pot- 

 ash, they dissolve in it. The fused mass is soluble in water. Hy- 

 drate of soda behaves in a different manner. When the ignited acids 

 are melted with it, the fused masses obtained are not clear ; but an 

 insoluble sediment is formed, which does not dissolve in any excess 

 of the alkali. If the fused mass be treated with a moderate quantity 

 of water, the excess of soda is removed, and a white insoluble mass 

 remains. If, after removing the free soda, a large portion of water 

 be poured over the insoluble mass, it dissolves, and most com- 

 pletely when niobic acid has been employed. 



The insolubility of the three acids in excess of soda, while the 

 potash compounds are soluble in excess of potash, essentially cha- 

 racterize them. In this they differ from similar acids, especially 

 from tungstic acid. When the solutions of the soda salts are mixed 

 with concentrated solutions of hydrate of soda, they immediately 

 become turbid ; if the mixture was made very slowly and carefully, 

 all three soda salts may be obtained in crystals, which are deposited 

 on the sides of the vessel. But crystals only of the niobate of soda 

 can be easily obtained of any size. I succeeded in obtaining them 

 half an inch and more in size, but in general they are much smaller. 

 They are sparingly soluble in cold, more readily soluble in hot 

 water ; the solution may be boiled without becoming turbid ; it can 

 be evaporated, and the niobate of soda deprived of its water of cry- 

 stallization without being decomposed. The salt is only rendered 

 insoluble in water by being heated to redness. 



The pelopate, and especially the tantalate of soda, are less stable ; 

 when their solutions are boiled, an insoluble white precipitate sepa- 

 rates, which is an acid salt of soda. 



When the niobate of soda is exposed to a red heat, and a current 

 of dry sulphuretted hydrogen passed over it, a dark black crystalline 

 mass is obtained, from which water removes hydrosulphated sul- 

 phuret of sodium, while crystalline sulphuret of niobium remains 

 undissolved. 



When pelopate of soda is treated in the same manner, there is 

 also no sulphosalt formed, but only sulphuret of pelopium. The 

 tantalate of soda remains white on treatment with sulphuretted hy- 

 drogen, but its soda is converted into sulphuret of hydrogen and 

 sodium. 



When niobic acid is fused with an excess of carbonate of soda 

 until the fused mass no longer decreases in weight, the amount 

 of oxygen in the expelled carbonic acid is twice that in the niobic 



