Chemical Science. 439 



bulk, is to be left for twenty-four hours at rest, in which time long 

 prismatic crystals will be produced, white, with a tinge of rose- 

 colour, and very brilliant. These are perfectly soluble in water, and 

 are reproduced by evaporation. Being heated on charcoal, they are 

 decomposed, one part subliming and the other being converted into 

 a metallic globule. On adding a little muriatic acid and a piece of 

 zinc to the aqueous solution, the zinc becomes covered with a dark 

 grey reduced metal. When the crystals are heated in a tube, the 

 substance subHmes entirely and unaltered, recrystallizing above. 



That this oxide in crystals is not a compound of osmium is proved 

 by its want of odour, and its distilling over in the solid instead of the 

 liquid form, which belongs to the latter. It is not an oxide of bis- 

 muth, tellurium or antimony, because it is entirely soluble in water. 

 A portion being sent to M. Berzelius, he confirmed the results of M. 

 Osaiin, and says, ** according to all the trials I have made to con- 

 vince myself, you have really found a new substance ; for the small 

 crystals which sublime, cannot be confounded with any other known 

 body. At first, I thought them to be oxide of tellurium or antimony, 

 but they do not sensibly dissolve in bi-hydro-sulphuret of ammonia, 

 but are converted into a grey metallic sulphuret. This sulphuret 

 easily fuses, becoming transparent and reddish yellow, but, on cool- 

 ing, acquires an opaque, metallic, grey appearance. It may be easily 

 roasted, and the oxide so produced sublimes at a dull, red heat. 

 This easy sublimation, and the properties of the sulphuret, prove 

 that the crystals are not a compound of bismuth." — Annalen der 

 Physik, 1828, p. 287. 



21. Preparation of Titanic AcidyhyM.Henn'Rose. — Pulverise and 

 wash menachanite, heat it highly in a porcelain tube, and pass dry 

 sulphuretted hydrogen gas over it : the oxide of iron will become 

 sulphuret, the titanic acid will remain unchanged. When cold, 

 digest the product in strong muriatic acid, sulphuretted hydro- 

 gen will be evolved, and the titanic acid, rendered insoluble by the 

 heat, and coloured grey by the sulphur, will remain. It is to be 

 washed, and heated red-hot, to drive off the sulphur. One opera- 

 tion is not sufficient to free the titanic acid perfectly from iron ; the 

 product is, therefore, again to be heated in a tube, through which 

 sulphuretted hydrogen is passing, and then treated as before ; 

 when, again washed and heated red-hot, it becomes perfectly white 

 and pure. 



Any titanic acid containing iron may be purified in this way. 

 The heat given to the substance, when in the tube, should be high, 

 or the titanic acid will render the washing water milky, and pass 

 through the filters. The operation may be shortened by heating 

 the titaniferous iron with sulphur in a crucible, and then acting by 

 concentrated muriatic acid ; but, in this first operation, as much 

 iron remains with the titanic acid as exists in rutilite : then, an ope- 

 ration with sulphuretted hydrogen, renders the substance perfectly 

 pure. — Annalen der Phys, 



