1814.] On the Cause of Chemical Proportions. 359 



riments of Dr. Jolin, as well as by some experiments which I have 

 made, that manganese has at least four degrees of oxidation, in the 

 proportion of 1, 2, 3, 4 : and as the tritoxide, or Mn + 3 O, is 

 composed of lOU metal and 42* 16 oxygen, it follows that the weight 

 of a volume of manganese is 'Jll-o'Jo. 



28. Cerium (Co). — Mr. Hisinger has found that 100 of muriatic 

 acid are neutralized by 196*18 of protoxide of cerium, and that the 

 percarbonate is composed of 63*83 oxide and 36" 1 7 of carbonic 

 acid. According to these experiments, 100 cerium form protoxide 

 by uniting with 17*41 of oxygen, and peroxide by uniting with 

 26'* 11 5 ; that is to sa}', with IJ- as much as in the protoxide. Hence 

 these oxides ought to be Ce + 2 O, Ce + 3 O. Therefore a 

 volume of cerium must weigh 1 148*8. 



29. Uranium (U). — Unknown. 



30. Ylirium (Y). — I decomposed dry carbonate of yttria in a 

 small retort furnished with a tubulated receiver, into the tube of 

 which I had put muriate of lime. When the retort began to soften 

 in the fire, I allo\.ed it to cool, and took out the earth, which I 

 exposed to a still stronger heat in a platinum crucible. 100 parts 

 of carbonate thus treated gave 12-82 of water and 57"7 of yttria. 

 Hence it is composed of 



Yttna 57-70 



Carbonic acid 29*48 



Water 1282 



100*00 



The 29*48 of carbonic acid contain 21*446 of oxygen; and as 

 the neutral muriate of yttria is precipitated by the carbonate of 

 ammonia without disengagement of carbonic acid, and as in this 

 carbonate tlie acid contains twice as much oxygen as the base, tlie 

 same thing must hold likewise in the carbonate of yttria. Therefore 

 57*70 of yttria ought to contain 10*723 of oxygen : so that this 

 earth contains 18*58 per cent. The 12*82 of water contain 11*3 

 of oxygen. We see from this circumstance that the carbonate had 

 not been entirely deprived of its adiierent water, but that in the 

 carbonate the water and earth must contain equal quantities of 

 oxygen. 



2*8 parts of yttria deprived of carbonic acid were dissolved in 

 pure sulphuric acid, the solution was evaporated to dryness, and the 

 sulphate licated till it ceased to give out acid vapours. Jt now 

 weighed 5*392 parts, and dissolved entirely in water. Sulphate of 

 yttria, then, is composed of 



Sulphuric acid 51*823 100 



Yttria 48*177 108 



100*000 



Now if 10* parts of yttria contain iy'96 of oxygen, 100 parts 



