18 1 4.1 On the Oxides of Arsenic. IT'S 



of 100 metal with about 50 oxygen. Other experiments made by 

 Berzelius served to confirm this conclusion. He found the arsenite 

 of lead to be a compound of 100 arsenious acid + 1 18-977 yellow 

 o\ide of lead. Now 118*977 parts of this oxide contain 8*5068 

 parts of oxygen; and 8*5068 x S = 25*5204; which number, 

 according to Ber/.elius' law, indicates the quantity of oxygen in 

 100 arsenious acid ; for in the arsenites the acid contains thrice as 

 much oxygen as the base According to this mode of reasoning, 

 the white oxide of arsenic is composed of 



Arsenic 74-48 100 



Oxygen 25*52 34*263 



Arseniate of lead, according to the analysis of the same accurate 

 experimenter, is composed of 



Arsenic acid 100*0 



Yellow oxide of lead 237*5 



Now in the arseniates the acid contains twice as much oxygen as 

 the base: 237'5 parts of yellow oxide of lead contain 16*981 parts 

 of oxygen; and 16-981 x 2 = 33-962. Therefore arsenic acid is 

 composed of 



Arsenic 66-03S 100 



Oxygen 33-962 51*428 



A conclusion which agrees sufficiently well with the analyses of 

 preceding experimenters. 



SucI) were the experiments hitherto made on the combination of 

 arsenic with oxygen. They seemed to leave no doubt that the 

 quantity of oxygen iu the white oxide was to that in arsenic acid as 

 two to three : and I considered it as established in my table pub- 

 lished in the Annals of Philosophy, ii. 42, that white oxide of 

 arsenic consisted of 100 metal + 33*333 oxygen, and arsenic acid 

 of 100 metal + 50 oxygen. 



But Berzelius has lately turned his attention again to this subject, 

 and published a new set of experiments, in which he has corrected 

 hi- former ones ; and he has drawn very different conclusions with 

 respect to the composition of arsenious and arsenic acids. (See 

 Annals of Philosophy, iii. 93.) >Je found by these experiments 

 that arseniate of lead is composed of 



Arsenic acid 100 



Yellow oxide of lead 194*11 



And arseniate of barytcs of 



Arsenic acid 100 



Baiytea 13270 



New 194*11 yellow oxide of lead contain 13*878 oxygen, and 

 132*70 barytes contain 18*89 oxygen. These quantities agree 



