1821.] Atomic Weight of various Mi't 'ah and Acids. 127 



I was obliged, therefore, to abandon the salts of mercury altoge- 

 ther. But the following experiment, which I repeated thrice, 

 with exactly the same result, appears to me sufficiently decisive 

 to settle the question respecting the composition of the oxides 

 of mercury, if there be any chemists who entertain doubts on 

 the subject. 



If an atom of mercury weigh 25, and if the red oxide of mer- 

 cury be a compound of one atom metal + two atoms oxygen, 

 it is obvious that an integrant particle of it must weigh 27. To 

 verify this, I put into an eight ounce phial 27 grains of peroxide 

 of mercury, and poured upon it a quantity of muriatic acid suffi- 

 cient to dissolve the oxide. The phial was then put upon a 

 sand-bath (having its mouth stopped by a charcoal stopper), 

 and left till the whole contents were evaporated to dryness. I 

 then covered it up about two-thirds with sand, the temperature 

 of which was gradually raised sufficiently high to sublime the 

 corrosive sublimate towards the middle of the phial. The whole 

 was then allowed to cool, and the phial being weighed, it was 

 found that the corrosive sublimate weighed exactly 34 grains. 



Now whether we take the view of the composition of corro- 

 sive sublimate deduced from Davy's theory of chlorine, or still 

 adhere to the old notion that it is a compound of peroxide of 

 mercury and muriatic acid, this experiment is decisive of the 

 weight of an atom of mercury. 



If we adhere to the old opinion, then corrosive sublimate is 

 composed of 



Peroxide of mercury 27 



Muriatic acid 7 



34 



But 3-5 (according to the old opinion) represents the weight 

 of an atom of muriatic acid. 'I he experiment shows us, there- 

 fore, that corrosive sublimate is a compound of two atoms 

 muriatic acid and one atom peroxide of mercury ; consequently 

 peroxide of mercury must weigh 27. 



If we adopt the theory of chlorine advanced by Davy, which 

 1 consider as much more consonant to the phenomena than the 

 old opinion, then corrosive sublimate is a compound of 



Mercury 25 



Chlorine 9 



~34 



But an atom of chlorine weighs 4*5 ; therefore, 9 represents 

 two atoms of chlorine ; consequently corrosive sublimate is a 

 compound of two atoms chlorine = 9, and one atom mercury 



= 25. 



