SILVKLJ. 433 



fore I thought of acidulating the water with nitric 

 acid. 



2. The preceding experiment gives us not 

 only the atomic weight of silver, but enables us 

 likewise to determine the atomic weight of oxide 

 of silver ; for it is obvious from it, that nitrate 

 of silver is anhydrous, and that 21-5 grains of it 

 contain exactly 13*75 grains of silver. Now, as 

 the salt is neutral, and as 13*75 is equivalent to 

 an atom of silver, it is obvious, that the 21*5 of 

 the salt must contain an atom of nitric acid ; 

 and that the difference between 21 '5 and 20*5, 

 (viz. 18-75 _j_ 6*75) must be the quantity of oxy- 

 gen with which the silver is united. Hence, ni- 

 trate of silver is composed of 



(of 1 atom silver 13-75) i 



1 atom oxide of silver -J > 14-75 



( 1 atom oxygen 1 ) 



I atom nitric acid . . . . .6-75 



21-5 



It is obvious, that the oxide of silver is a com- Atom of 



, oxide of sil- 



pound of 1 atom silver + 1 atom oxygen, and ver . 

 that its atomic weight is 14*75. 



3. When oxide of silver is dissolved in ammo- Suboxide 

 nia, and the solution left exposed to the air, a 

 brilliant black pellicle collects on the surface. 

 This pellicle was first examined by Mr. Faraday, 

 from whose experiments it appears, that it con- 

 tains two thirds of the oxygen in the common 

 oxide of silver. My experiments on this pellicle, 



VOL. I. E c 



