16 Oxide of Silver In Ammonia. [1818. 



which gave rise to the idea of its being a combined protoxide, 

 might be explained by the further formation of a portion of 

 oxide similar to that already described. 



The method of obtaining this compound has been to pre- 

 cipitate oxide of silver from the nitrate by alkalies, or better, 

 by lime-water, to wash and dry it well, and then to leave it in 

 contact with liquid ammonia for ten or twelve hours ; the 

 greater part is dissolved, but a black powder remains, which 

 is fulminating silver ; if the solution be heated, azote is given 

 off, and a further quantity of fulminating silver is obtained 

 (Annales de Chimie, tome i.). 



I find that fulminating silver may be formed from any 

 precipitated oxide of silver, whether moist or dry, recent or 

 old. Boil the oxide carefully in a tube with a mixed solution 

 of potash and ammonia for a few moments ; the potash absorbs 

 all the carbonic acid that may have been united to the oxide, 

 and to a certain degree prevents its solution in the ammonia ; 

 a black powder, similar to that procured by the other process, 

 results. 



In order to gain some evidence respecting the nature of the 

 oxide combined with the ammonia in fulminating silver, I 

 endeavoured to ascertain the mode of formation of that com- 

 pound. It appears to be formed in every case where common 

 oxide of silver is dissolved in ammonia, and the entire solution 

 of all solid matter is no evidence of its non-existence, for the 

 compound is itself soluble in ammonia, though not so much so 

 as the oxide. When there is an excess of oxide, unless it 

 predominate in a great degree, the undissolved portion will be 

 found to contain fulminating silver, and when the whole is dis- 

 solved, by heating the solution, it is thrown down. 



To ascertain whether the liberation of azote depended upon 

 the formation of the fulminating compound, I boiled, for a 

 few moments, a solution of the oxide in ammonia; the solu- 

 tion became highly coloured, azote was given off, and a black 

 curdy precipitate formed, which left the liquid colourless ; 

 separated by a filter, the precipitate proved to be fulminating 

 silver. The solution was again heateo 1 , it again blackened, 

 gave off azote, and again a precipitate formed ; this was not 

 fulminating silver, but merely oxide : filtered and again heated, 

 it gave off azote, and more of the oxide was formed ; and this 



