418 Intelligence and Miscellatieous drticles. 



they are reduced to a soft powder. The acid prepared by the second 

 process forms white firm masses which have a conchoid al fracture 

 and no lustre. 



During calcination, ilmenic acid assumes a fine golden tint; and 

 the acid obtained" from the hydrate becomes, under these circum- 

 stances, of a deeper colour than the acid prepared by calcining the 

 subsulphate. On cooling, the ilmenic resumes its white colour per- 

 fectly. Its specific gravity is from 4*10 to 4 - 20. 



Hydrate of ilmenium is precipitated when excess of hydrochloric 

 acid is added to a solution of ilmenate of soda ; it is a white, dia- 

 phanous and gelatinous precipitate, which dries in opake compact 

 pieces. 



Ilmenic acid does not dissolve in concentrated sulphuric acid, but 

 at a red heat it fuses readily with bisulphate of potash or soda, yield- 

 ing a limpid product which is yellow while hot and becomes colour- 

 less on cooling. After washing this product, the ilmenic acid re- 

 mains perfectly insoluble, in combination with sulphuric acid, forming 

 a thick white precipitate, which leaves on drying white pieces of an 

 earthy fracture. 



Ilmenic acid has but slight affinity for sulphuric acid ; by long- 

 continued washing it separates from it perfectly, and is converted 

 into hydrate. 



A portion of sulphate of ilmenium, the last washings of which still 

 retained traces of sulphuric acid, was dried at 122° F. ; and was then 

 found to consist of ilmenic acid 77*63, sulphuric acid 7'69, water 

 14'68. 



Subsulphate of ilmenium even while moist is totally insoluble in 

 hot concentrated hydrochloric acid ; this property distinctly marks 

 the difference between ilmenic and niobic acid. Subsulphate of il- 

 menium readily loses the whole of its sulphuric acid at a red heat. 



Chloride of ilmenium is prepared like the chloride of columbium ; 

 it is deposited in the cold part of the porcelain tube like hoar-frost, 

 composed of yellowish translucent prisms ; in a moist atmosphere 

 this salt exhales hydrochloric acid vapours ; it then becomes white 

 and opake; when thrown into water it is decomposed, with the 

 evolution of much heat, and with the production of hydrochloric acid 

 and diaphanous colourless flocks of hydrate of ilmenium. It absorbs 

 ammonia with great avidity and the disengagement of considerable 

 heat ; a yellow mass is also produced, which by calcination in vacuo 

 is converted into hydrochlorate of ammonia and ilmenium. 



Equal parts of ilmenic acid and dry carbonate of soda, heated 

 strongly to redness, lost carbonic acid equal to 29*1 per cent, of the 

 weight of the ilmenic acid. 



Ilmenate of soda is a gray mass with an earthy fracture ; when 

 boiled in water it is decomposed into soluble subilmenate of soda and 

 a superilmenate which is deposited in the state of a white powder. 



Excess of either nitric or hydrochloric acid completely precipitates 

 the ilmenic acid from ilmenate cf soda ; this circumstance distin- 

 guishes it essentially from columbic and niobic acids, which remain 

 partly in solution. 



A concentrated solution of ilmenate of soda does not yield cryste 1 * 



