FULMINIC ACID. 995 



acid, it assumes the elements of 2 atoms of water, and is con- 

 verted into carbonic acid and ammonia. 



Nitrate of urea is soluble in 8 parts of cold water. It con- 

 sists of single equivalents of urea, nitric acid and water. 

 (Regnault). 



Oxalate of urea crystallizes in long thin prisms, which are 

 much less soluble in water than the nitrate, and have an acid 

 taste. This salt also contains an atom of water. From the 

 oxalate of urea, compounds of urea with other acids may be ob- 

 tained, by precipitating the oxalic acid with a neutral salt of 

 lime of the other acid, and thus the hippurate, lactate, sulphate, 

 &c. have been formed and crystallized by MM. Cap and 

 Henry. 



FULMINIC ACID. 



Formula of the acid supposed anhydrous : C 4 N 2 O 2 =Cy 2 O 2 . 



Fulminic acid exists in certain fulminating compounds of 

 silver and mercury, discovered by Mr. Howard, but its true 

 nature was first ascertained by Gay-Lussac and Liebig. The 

 acid is bibasic ; it undergoes decomposition when separated 

 from bases by a stronger acid, into hydrocyanic acid and other 

 products. Fulminic acid is formed by the action of an excess 

 of nitric acid and alcohol upon nitrate of silver or nitrate of sub- 

 oxide of mercury. A variety of products result from the mutual 

 action of nitric acid and alcohol, including nitrous acid ; 2 atoms 

 of which with 1 atom of ether are resolved, in contact with 

 oxide of silver or mercury, into water and fulminic acid, the last 

 combining with the metallic oxide : 



Nitrous acid. Ether. Fulminic acid. 



N 2 O 6 and C 4 H 5 0=C 4 N 2 O 2 and 5HO. 



Fulminate of silver is also immediately formed and precipitated 

 on transmitting the vapour of nitrous acid through a saturated 

 solution of nitrate of silver in alcohol. 



Fulminates. The salt of suboxide of mercury is prepared by 

 dissolving 1 part of mercury in 12 parts of nitric acid of 1.36, 

 by a gentle heat; then adding 1 1 parts of alcohol of 0.848, and 

 heating by a water-bath. A violent reaction soon occurs, with 



2 T T 2 



