igS Account of Experiments 



carrying with it a little iron, which gives it a slight tint of 

 a rose colour : it is soluble in acids. The tartrites form a 

 precipitate much less soluble, which does not contain iron; 

 but it is entirely soluble in caustic alkalies as well as in an 

 excess of its concentrated acid, from which it is afterwards 

 separated by water. Phosphates occasion a precipitate 

 which is not soluble in acids without the aid of heat : iron 

 remains in intimate combination with it. Pruasiatcs preci- 

 pitate solutions of cerium white, even when they contain evi- 

 dent traces of iron. All the precipitates here spoken of are 

 white, and retain that colour after desiccation, except the 

 phosphate, which becomes grayish. Sulphurets and hy- 

 dro-sulphurets precipitate solutions of cerium white: the 

 precipitates when washed retain their white colour in dry- 

 ing, and dissolve in acids with effervescence : carbonic acid 

 is disengaged, but not an atom of hydrogenatcd sulphuret ; 

 which proves that cerium does not unite with sulphurized 

 hydrogen. 



Zinc, tin, and iron, immersed in a solution of muriate 

 of cerium, do not effect a reduction of it. They precipitate 

 a black matter, which is in too small quantity to be ana- 

 lysed : there is deposited at the same time a white powder, 

 which appears to he an Oxide of the precipitating metal. 



An alcoholic solution of gall-nuts produces in muriate of 

 cerium a yellowish precipitate not very abundant. The ad- 

 dition of a few drops of ammonia determines a very volu- 

 minous one of a brown colour, which becomes black and 

 brilliant by desiccation : by the action of heat it resumes n 

 beautiful brick red colour. 



When the silex extracted from cerlte is fused with an 

 alkali, it is observed that the mixture assumes a beautiful 

 pale straw^ colour, which soon passes to brown : if the sur- 

 faces be often renewed the whole matter becomes brown, 

 but by adding a little charcoal this colour vanishes entirely. 

 Having made these preliminary trials on cerite, and ascer- 

 tained 'the principal properties of the particular substance 

 which it contains, I undertook to analyse it, in regard to 

 quantity, in the following manner : 



A hundred parts of this mineral in fine powder were 

 mixed with ten times their weight of nitro-muriatic acid, 

 asid subjected to ebullition for an hour: the mixture being 

 -diluted with water, and filtered, left on the filter a brown 

 dust, which was dried, and fused with caustic potash. The 

 mixture being diluted with water, and then dissolved in 

 muriatic acid, evaporated to dryness, and redissolved in 

 water, left a powder which when collected on a filter, 



washed. 



