82 URANIUM, ANTIMONY, CHROMIUM, &c. 



snow white. It possesses the properties of a 

 weak acid, and has in consequence been called 

 titanic acid by M. H. Rose, to whom we owe by 

 far the best set of experiments hitherto made 

 on it.* Titanic acid occurs native in the form 

 of long prisms, or needles having usually a red- 

 dish colour, and therefore called red schorl. 

 It is never quite pure, being always combined 

 with peroxide of iron ; though hitherto no good 

 method has been discovered of separating per- 

 oxide of iron from titanic acid, and determining 

 the quantity of each. Titanic acid occurs, like- 

 wise, united to a considerable proportion of per- 

 oxide of iron in black grains like gunpowder, 

 and distinguished by the names of menaccanite, 

 nigrine, and iserine, according to the size of the 

 grains. 



2. M. H. Rose is the first chemist who ob- 

 tained titanic acid in a state of purity. It will 

 be proper, therefore, to state his mode of pro- 

 ceeding before attempting to investigate the 

 atomic weight of this substance. He employed 

 rutile or red schorl for this purpose. The 

 mineral was reduced to a fine powder, and fused 

 with thrice, its weight of carbonate of potash, 

 The mass was softened with water, and the com- 

 pound of titanic acid, peroxide of iron, and pot- 

 ash was dissolved in muriatic acid, and mixed 



* Kong. Vetensk, Acad. Hand. 1821, p. 231. 



