160 CERITE. 



THE HYDRATED PROTOXIDE OF CERIUM is colorless, 

 but oxidizes rapidly on exposure to air, and becomes 

 yellow. It is obtained by igniting the carbonate of 

 oxalate in a current of hydrogen, is bluish-gray, and 

 oxidizes in the air to a yellowish-white compound of 

 oxide and sesquioxide, or by heating to an orange-red. 

 It is insoluble in nitric and hydrochloric acids, but 

 soluble in sulphuric with a yellow color. 



THE SESQUIOXIDE OF CERIUM, in the pure state, is 

 yellow, with a tinge of red ; when impure, it is brick- 

 red. It is produced when the hydrate is ignited in 

 air. The sesquioxide is soluble only in hot concen- 

 trated sulphuric acid; the solution has a fine yellow 

 color. The hydrated sesquioxide is dissolved, in quan- 

 tity, with a yellow color, by the alkaline bicarbonates, 

 especially by bicarbonate of ammonia. The sesqui- 

 oxide is insoluble in concentrated hydrochloric acid, 

 but on addition of alcohol, it is dissolved in the form 

 of protochloride. 



OXIDE OF LANTHANUM is colorless; when heated 

 with water, it is converted into the hydrate, which has 

 an alkaline reaction. It is dissolved by a hot solution 

 of chloride of ammonium, with evolution of ammonia. 

 Its salts are colorless. The carbonate is insoluble in 

 carbonate of ammonia. 



OXIDE OF DIDYMIUM, when ignited, is brown. 

 When exposed to a white heat it assumes a dingy 

 white color, with a tinge of green. It is soluble in 

 acids; its salts have the color of amethyst, with a tinge 

 of blue ; with hydrate of potassa they yield a violet 

 hydrate. The carbonate is insoluble in carbonate of 

 ammonia. 



The ignited brown mixture of the three oxides is 

 dissolved by hydrochloric acid, with evolution of 

 chlorine. 



If the mixed hydrates, precipitated by potassa, be 

 dissolved in nitric acid, the solution evaporated to 



