412 Intelligence and Miscellaneous Articles. 



Chloride of tantalium dissolves in hydrochloric acid in the cold to 

 a turbid liquid, which after some length of time forms an opaline 

 jelly, from which cold and boiling water dissolve only traces of tan- 

 talic acid. But if chloride of tantalium is treated with boiling hy- 

 drochloric acid, it does not dissolve entirely, and on cooling it does not 

 form a jelly, but water now dissolves the whole of it to an opaline 

 liquid, which is not rendered more turbid by boiling. Sulphuric 

 acid produces in it, after some time, a voluminous precipitate even 

 in the cold. The chloride of pelopium behaves in a similar manner, 

 except that sulphuric acid does not produce a precipitate in the cold 

 in the solution obtained by boiling and diluted with water, but only 

 on boiling. Chloride of niobium does not dissolve in cold hydro- 

 chloric acid ; scarcely anything is dissolved on the addition of water ; 

 when however chloride of niobium is boiled with hydrochloric acid, 

 it does not dissolve in it, but on diluting with water the whole 

 dissolves, and the niobic acid is not even precipitated from the solu- 

 tion by boiling. When however sulphuric acid is added, a turbid- 

 ness results even in the cold, and the whole of the niobic acid is 

 precipitated by boiling. When, on the other hand, but a small 

 quantity of hydrochloric acid is placed in contact with the hydrates 

 of the acids, the result is quite a different one. The same is the 

 case when the chlorides of the three metals are treated with much 

 water. The niobic acid is then completely separated on boiling from 

 the chloride of niobium, and also the pelopic acid from the chloride 

 of pelopium ; but tantalic acid does not separate quite so completely 

 from the chloride of tantalium. 



Chloride of tantalium, heated with a solution of hydrate of pot- 

 ash, is partly dissolved ; but a solution of carbonate of potash does 

 not dissolve any tantalic acid even on boiling. Chloride of pelopium 

 is dissolved in large quantity by solution of caustic potash, and even 

 carbonate of potash dissolves it in tolerable abundance on boiling. 

 Chloride of niobium is dissolved even in the cold by a solution of 

 potash, and also by boiling in a solution of carbonate of potash. 



Tantalic acid remains white on being heated to redness ; pelopic 

 acid is rendered slightly yellowish ; niobic acid, dark yellow. On 

 cooling, both again become as white as before ignition. 



All three acids exhibit, when their hydrates are heated very 

 strongly, the phenomenon of incandescence. This however is not 

 the case when the compounds with sulphuric acid are treated with 

 ammonia, and then heated to redness. • 



Tantalic acid, exposed in a current of hydrogen to a strong red 

 heat, remains white ; pelopic and niobic acids become black ; but 

 the reduction which these acids undergo is quite inconsiderable, 

 for very doubtful traces of water are perceptible, and the blackened 

 acids quickly become white when heated with access of air, without 

 experiencing any perceptible increase in weight. When tantalic acid 

 is heated to redness in a current of gaseous ammonia in a brisk 

 charcoal fire, it is turned gray, with the formation of but slight 

 traces of water. Pelopic and niobic acids become black, and are 

 reduced, with the production of a considerable quantity of water. 



When tantalic acid is heated in a brisk charcoal fire, and sulphu- 



