220 CYANOGEN COMPOUNDS. 



Strongly alkaline liquid, which attracts carbonic anhy 

 dride from the air, and then crystallizes. 



Fulminic acid, C 2 H 2 N 2 2 .* In a free condition, 

 unknown. Cannot be isolated from its salts. 



Mercury fulminate (Fulminating mercury), 

 2 IIg + H 2 0, is formed by the spontaneous heating of a 

 mixture of mercury nitrate, excess of nitric acid and 

 alcohol. 1 part mercury is dissolved in 12 parts nitric 

 acid of specific gravity 1.36, this solution poured 

 into 5J parts of alcohol (90 Tralles), and the vessel 

 shaken violently. In a short time reaction begins, 

 which becomes more violent very rapidly, and is mode 

 rated by the gradual addition of 6 parts alcohol of the 

 same strength as that first employed. The black color, 

 which at first makes its appearance from the presence 

 of metallic mercury, soon disappears, and crystalline 

 flocks of mercury fulminate separate, which are puri 

 fied by recrystallization from hot water. White, silky 

 needles, sparingly soluble in cold water, easily in hot. 

 Heated or forcibly struck, it detonates with a loud 

 report. Copper and zinc, boiled in water with fulmi 

 nating mercury, decompose the latter substance, yield 

 ing metallic mercury and copper and zinc fulminate. 

 Sulphuretted hydrogen precipitates the mercury from 

 the solution, but the liberated acid is immediately 

 decomposed by sulphuretted hydrogen into carbonic 

 anhydride and ammonium sulphocyanate. Free bro 

 mine forms mercury bromide and methyl dibromnitro- 

 cyanide CW^O 2 = C(^&quot;0 2 )Br. 2 CN (large crystals, 

 fusing at 50), together with cyanogen bromide, hydro- 

 bromic acid, and other products. 



Silver fulminate (Fulminating silver), C 2 ^T 2 2 Ag 2 , 

 is obtained in the same manner as fulminating mer 

 cury, and is very similar to the latter in all its pro 

 perties. Potassium chloride precipitates only half the 

 silver from a boiling solution, and, on the evaporation 



* Probably nitrocyanmethyl C(N02)(CN)H2. 



