414 Intelligence and Miscellaneous Articles. 



acid employed. The results obtained on fusing pelopic and tan- 

 talic acids with carbonate of soda did not agree. By long-con- 

 tinued fusion of tantalic acid with carbonate of soda, so much car- 

 bonic acid is expelled that its amount of oxygen was equal to that 

 of the tantalic acid employed, and finally exceeded it. But never- 

 theless this basic salt does not dissolve undecomposed in water, but 

 leaves a considerable residue of acid tantalate of soda. Something 

 similar takes place with pelopic acid, only the basic pelopate of 

 soda formed dissolves entirely in water. 



When the three acids are fused with carbonate of potash, they 

 exhibit similar properties ; but the potash salts are as soluble 

 in the excess of carbonate of potash as in hydrate of potash. In 

 this way we obtain compounds which are soluble in water and cry- 

 stallize ; but they contain carbonate of potash, which cannot be 

 separated in any manner. 



The combinations of tantalic acid with the alkalies are charac- 

 terized by their passing on all occasions into insoluble acid salts, 

 especially on boiling and evaporating their solutions. The solutions 

 of the alkaline pelopates exhibit this property in a far less degree, 

 those of the niobates not at all. Insoluble acid niobates of potash or 

 soda can only be produced by not fusing the acid a sufficient time 

 with the carbonates. 



Tantalic acid is soon and entirely precipitated from its alkaline 

 solutions by carbonic acid as an acid salt ; the same is the case with 

 pelopic acid, but with greater difficulty and far more slowly. It is 

 , owing to this that the neutral solution of tantalite of soda becomes 

 turbid even by exposure to the air, while that of the pelopate of 

 soda does not become turbid even after long exposure, which is 

 characteristic of it. Carbonic acid produces a precipitate in the 

 solution of alkaline niobate only after a considerable length of time, 

 which however is again dissolved by much water. 



When the solutions of the alkaline tantalates and pelopates are 

 treated with an excess of hydrochloric acid, the eliminated acids 

 dissolve to faintly opaline liquids. Sulphuric acid produces in these 

 solutions precipitates, and separates the acids on boiling ; however, 

 only the pelopic acid entirely, and not so the tantalic acid. Hydro- 

 chloric acid precipitates the acid from the solutions of the alkaline 

 niobates in the cold, and still more so on boiling; an excess of hy- 

 drochloric acid merely dissolves slight traces. This behaviour is 

 in so far interesting, as we have seen that under other circumstances 

 niobic acid may be wholly soluble in hydrochloric acid. Sulphuric 

 acid precipitates niobic acid from its alkaline solutionseven inthecold. 



From the solutions of the alkaline tantalates the acid is entirely 

 precipitated, without the assistance of heat, by chloride of ammo- 

 nium, pelopic acid less perfectly, and niobic acid still less. 



When the solutions of the alkaline tantalates are rendered acid 

 with hydrochloric or sulphuric acid, a pale yellow precipitate is pro- 

 duced in them by tincture of galls. An orange-yellow precipitate 

 is formed, under similar circumstances, in solutions of the pelopates, 

 and a dark orange-red in those of the niobates. 



