356 On the Quantity of Oxygen [Nov. 



by carbonate of ammonia. This precipitate, being heated to redness 

 in a close vessel to expel all the alkali, weighed 684 gramme 

 (10-01 grain). 



Now as 100 parts of fused muriate of silver contain 1 9*05 parts 

 of muriatic acid, and as 684 parts of oxide of cerium combine 

 with a quantity of muriatic acid which forms 1819 parts of muriate 

 of silver, it follows that 684 parts of oxide of cerium combine with 

 346*5 parts of muriatic acid. Therefore muriate of cerium is 

 composed of 



Muriatic acid 33-624 100 



Oxide of cerium 66-376 197*5 



100-000 297*5 



But as 100 parts of muriatic acid are saturated by a quantity of 

 base containing 29*45 parts of oxygen, it follows that 197*5 parts 

 of oxide of cerium must contain 29 '45 of oxygen. Hence 100 

 parts of this oxide consist of 



Metal S5-088 100 



Oxygen 14*912 17*41 



100*000 117*41 



Farther, as by the laws established in the dissertation of Berzelius 

 above referred to, an oxidule, in order to be converted into an 

 oxide, combines either with half the quantity of oxygen which it 

 already contains, or with an equal quantity, it is evident that the 

 peroxide of cerium must be composed of 100 parts metal united 

 either with 26*115 or with 34*82 parts of oxygen. 



The analyses of the carbonates appear to prove that the peroxide 

 of cerium contains 14- times as much oxygen united to the same 

 quantity of metal as the protoxide. 



I have (in the Afhandl. i Fysik Kemi och Mineralogie, 3 D. sid. 

 2S7,) given an analysis of the oxides of cerium united with car- 

 bonic acid ; and I found that the procarbonate, which, when 

 decomposed in a retort, gives very evident indications that it 

 contains water, leaves 57'9 parts of pure protoxide. Thq experiments 

 of Berzelius appear to show that carbonic acid neutralizes a quantity 

 of base containing half as much oxygen as exists in the acid, and that 

 the chemically combined water, in like manner, contains a quantity 

 of oxygen which is a multiple of that contained in the acid. If we 

 reckon t he constitution of the procarbonate of cerium according to 

 these principles, it is obvious that the 42*1 parts driven off by the 

 heat must consist of 23 parts of carbonic acid and 19*1 parts of 

 water; 57'9 parts of the protoxide contain 8-63 parts of oxygen; 

 and 23 parts of carbonic acid (reckoning the oxygen at 73 per 

 cc t.) contain 16*19 oxygen, while 19-1 parts of water contain 

 of oxygen. These two quantities (abstracting the small 

 SO'- 1 sacb double the quautity ol oxygen in the protoxide. 



