30 C H E M I 



Klrmnt 4. The simple incombustibles do not unite with it, 

 but it combines with the metals and forms alloys, 

 hitherto examined only by the Elhuyarts. 



Titanium. 



Tolum- 



bium. 



'Cerium. 



SECT. XXV. Of Mania**. 



This metal was discovered by Mr Gregor ; but it 

 received its name from Klaproth, who discovered it 

 without any knowledge of the labours of Gregor. 



1 . 1 1 is so refractory that most persons have failed 

 in their attempts to reduce it. Lampadius is said to 

 have succeeded. Its colour is that of copper, and it 

 has considerable lustre. It is brittle, but elastic. 



2. It is easily oxidized by exposure to heat and 

 air. We know three oxides of titanium, the blue, 

 the red, and the tvhite. 



The protoxide, which is Hue, or purple, is formed 

 by exposing titanium hot to the open air. 



The red oxide is found native. It is often crys- 

 tallize.l in four-sided prism*. Its specific gravity is 

 4.2, and it is hard enough to scratch glass. By a 

 very violent heat it seems to be partially oxidized. 

 It appears to be composed of 100 metal and 33 oxy- 

 gen. 



The peroxide, or white oxide, may be obtained by 

 fusing the red oxide in a crucible with four times its 

 weight of potash, and dissolving the whole in water. 

 A white powder gradually precipitates, which is the 

 oxide in question. It is composed of about two 

 parts metal and one oxygen. 



.'). Titanium has been combined with none of the 

 simple combustibles except phosphorus. The phos- 

 phuret is of a white colour, brittle, and granular, and 

 doe<) not melt before the blowpipe. 



4. Hitherto titanium has been alloyed with none 

 of the metals, except iron. 



SECT. XXVI. Of Columbium. 



This metal was discovered by Mr Hatchett during 

 the analysis of an ore from America, deposited in the 

 British museum. He obtained from the mineral a 

 white powder, which possessed acid properties pecu- 

 liar to itself. He shewed that this powder was a 

 metallic oxide j but all attempts to reduce it to the 

 metallic state were unsuccessful. We are at present 

 ignorant of the properties of this metal. 



Ekeberg, a Swedish chemist, announced, some 

 years ago, that he had discovered a peculiar metal, 

 to which he gave the name of tantalum. Dr Wol- 

 laston has lately proved, that this new metal is the 

 same with Mr Hatchett's columbium. 



SECT. XXVII. Of Cerium. 



This metal was discovered by Hisinger and Berze- 

 lius in a mineral found in a Swedish copper mine, 

 and at first confounded with tungsteu. To procure 

 the oxide of cerium is easy, but all attempts to re- 

 duce that oxide to the metallic state have failed. 

 The metal appears to be volatile, and is dissipated by 

 a violent heat, while a moderate heat is not sufficient 

 to reduce it. 



1. Cerium appear* to be white and brittle j but it* 

 ether properties are unknown. 



S T R V. 



2. It forms, at least, two oxides, the lehiie and the Elements 

 red; and, according to the Swedi.-h chemists, there 

 are two nxult s intermediate between these, the yd- 

 loir and the brown. 



S. We are unacquainted with the effect of the 

 simple combustibles and incombustiblcs on cerium. 

 It has been alloyed with iron, but with no other me- 

 tal. 



SECT. XXVIII. General Remarkt. 



The following Table exhibits a synoptical view of 

 ome of the principal properties of the metals. 



