260 HISTORICAL INTRODUCTION TO CHEMISTRY CHAP. 



(" On the Fulminating Calx of Gold," Bergman's Essays, II., 

 134-165 ; pp. 155, 156). He also drove off the volatile 

 alkali by gentle heat, when the gold lost its power of 

 detonating (loc. cit. p. 145), and remained in the form of an 

 inert calx, the " aurum mutum " of the alchemists. When the 

 fulminate is detonated, the oxygen of the calx combines 

 with the inflammable constituent of the ammonia, the inert, 

 gaseous constituent is suddenly set free, and a residue of 

 metallic gold remains. 



Scheele in the course of his Experiments on Air and Fire 

 confirmed Bergman's observations and actually extracted a 

 small quantity of ammonia from the fulminate. Following 

 Bergman he detonated half a drachm of fulminating gold 

 over water and obtained six ounce-measures of a gas, which 

 had the following properties : 



was not miscible with water. 



did not precipitate lime-water. 



"(3) It extinguished immediately the flame of a burning 

 candle ; and was consequently air, in every respect, 

 similar to that generated by the destruction of volatile 

 alkali " (Experiments on Air and Fire, tr. J. R. Forster, 

 1780, pp. 142-143). 



The liberation of gas by the action of chlorine on 

 ammonia is noted in his essay "On Manganese" (Essays, 

 p. 71). 



Berthollet (1785) proves that ammonia is a compound of 

 hydrogen and nitrogen. To the French chemist Berthollet 

 belongs the credit of proving definitely in 1785 that the 

 inflammable constituent of ammonia is hydrogen, and the 

 inert constituent nitrogen. He also made an accurate 

 quantitative analysis of the gas. 



The nature of the inflammable constituent was determined 

 by neutralising the ammonia with nitric acid and heating the 

 crystalline nitrate thus produced. Nitrous oxide was set 

 free, and a considerable volume of water was condensed. 



"(i) It wa 

 "(2) It di< 



