1814.] in the Oxides of Cerium. 357 



Now it is obvious that the anomaly cannot occasion any difficulty, 

 as it is within the limits of the errors of the analysis itself. 



I found the percarbonate composed of 63*83 parts of oxide and 

 36*17 parts of carbonic acid. This quantity of acid contains 25-50 

 of oxygen, one half of which = 13-25 must exist in the 63 83 

 parts of oxide. Hence that portion of oxide contains 50-58 parts of 

 metal; but 5058 : 13-25 :: 100:26195. Now 17-41, or the 

 quantity of oxygen combined with 100, metal in the protoxide 

 multiplied by li = 26-115. 



We cannot certainly expect a nearer coincidence than this 

 between calculation and experiment. Of consequence the peroxide 

 of cerium must be compused of 



Metal 79-29 lOO'OOO 



Oxygen 20-71 26-115 



100-00 126-115 



Article VII. 



Experiments to determine the Proportion in which Bismuth unites 

 with Sulphur and Oxygen. By P. Lagerhjelm.* 



1. With Sulphur. 



The bismuth of commerce was boiled in a solution of aqua regia. 

 The solution, being saturated with ammonia, and mixed with some 

 prussiate of potash, gave a Berlin blue precipitate, indicating the 

 presence of iron. The bismuth was reduced to a state of purity by 

 the following method : — 



The aqueous solution was precipitated by water. The precipitate 

 was edulcorated, and dried by the heat of a stove. Seven parts of 

 this dry mass were mixed with one part of charcoal powder and five 

 parts of black flux. This mixture was put into a large crucible, and 

 exposed to a red heat for a quarter of an hour. There were obtained 

 y of pure metal. 



The sulphur which was employed in the following experiments 

 was partly roll sulphur purified by distillation, partly native sulphur. 

 It was heated before each experiment, sometimes nearly to the 

 melting point, and sometimes it was rendered quite liquid, for its 

 more commodious application to the metal. 



Into a dry glass vessel, weighing 2*!*79 grammes, there were put 

 10,000 grammes of metal in the state of a fine powder, and abun- 

 dance of sulphur. The glass vessel was heated over a spirit lamp 



• Translated from llic Kongl. Vetenskapi Acaderoiens Handlingnr, for 1813, 

 Fart 11. o. V\9. 



