14 Oxide of Silver in Ammonia. [1818. 



loss being supposed to be water, some of which had condensed 

 in the neck of the retort. Now 



Oxygen. Silver. Oxygen. Silver. 



-935 18 7-5 



The same method of analysis was applied to oxide of silver, 

 precipitated by potash from nitrate of silver, it having been 

 well washed and dried : 40 grains gave 7*9 cubical inches, and 

 36*4 grains of silver remained. The 7*9 cubical inches = 2*686 

 grains, and 



Oxygen. Silver. Oxygen. Silver. 



2-686 36-4 7-5 101-6, 



the number for silver very nearly as given in the most correct 

 elementary treatises on chemistry. There appears, therefore, 

 to be no error in the mode of analysis, and the oxide by am- 

 monia seems to contain less oxygen than that precipitated by 

 alkalies. Again, 



30 grains of the oxide of silver were put into a retort, and 

 decomposed with every precaution as before ; the silver left 

 weighed 27*4 grains, and the quantity of gas given off was 4*125 

 cubical inches. I suspected that a small portion of carbonate 

 of silver had been mixed with the oxide, for when the ammo- 

 niacal solution has been long exposed to the air, much carbo- 

 nate of ammonia and of silver is formed in it ; the gases were 

 therefore placed over solution of potash, and were reduced in 

 bulk to 3-625, which was pure oxygen. This volume is equi- 

 valent to 1-2325 gr., and 1-2325 : 27'4 : : 7'5 : 166-7, a propor- 

 tion of silver still higher than in the first experiment, but 

 which may be accounted for by the purification of gas and the 

 small quantity of oxygen that remained in the retort. 



In a third experiment, 24 grains of silver were left ; 4*25 

 cubical inches of gas were given off*, which decreased over 

 potash to 4. In order to estimate the proportion of azote 

 arising from the air in the retort, the 4 were treated with 

 nitrous gas of known purity, and gave results equal to 3*475 

 of pure oxygen. This is equal to 1*1815 gr., and 1*1815 : 24 

 : : 7-5 : 152'3. 



One or two other experiments varied considerably from 

 this, giving a greater proportion of silver, but the mean of 

 many gave the oxygen to the silver as 7*5 to 157*4. 



