474 NITRATE OF AMMONIA. 



composed of 1 proportion of soda 32, and \ of nitric acid 54 = 86, 

 its equivalent. 



4. USES. Proust suggested that, for economy, it might be em- 

 ployed in artifical fire works, and that 5 parts of it, with 1 of char- 

 coal and 1 of sulphur, will burn three times as long as common gun- 

 powder, and of course make a more enduring exhibition. When 

 thrown on a shovel full of burning coals it produces a peculiar orange 

 yellow flame. 



5. NATURAL SOURCES. It had been thought that this salt was un- 

 known as a natural production, but it has been, within a few years, 

 discovered in Peru, in the district of Atacama, near the port of 

 Yquique ; it is in strata of variable thickness, under clay, extending 

 fifty leagues, and in some places it is quite pure. The proprietor had, 

 at the date of the account, obtained from it 40000 quintals.* 



NITRATE OF AMMONIA. 



1. HISTORY AND NAME. Long known ond formerly called nitrvm 

 flammans and semivolatile. Our accurate knowledge of its properties 

 is derived, principally, from Berthollet and Davy. 



2. PREPARATION. 



(a.) Bring into contact, in a glass globe with two necks, the vapor 

 of strong nitric acid and ammoniacal gas, (in an apparatus like that 

 on p. 385,) when nitrate of ammonia will be precipitated, at first 

 concrete, but which will soon deliquesce and then crystallize in prisms. 



(b.) The best mode is to saturate diluted nitric acid with con- 

 crete carbonate of ammonia; evaporate with a gentle heat and crys- 

 tallize, f If the evaporation has been performed between 70 and 

 100 Fahr. the crystals are hexahedral prisms crowned by long 

 hexahedral pyramids; if at 212, they are in silky fibres; if at 300, 

 the solution concretes without crystallization. 



3. PROPERTIES. 



(a.) Taste, bitter and cool. Sp.gr. 1.5785. 



(b.) Soluble at 60, in twice, and at 212, in half its weight of 

 water ; f deliquescent. 



(c.) The acids, especially the sulphuric, decompose it. 



The fibrous or prismatic crystals melt at 230, or below 300 ; 

 ebullition, but without decomposition, commences between 360 and 

 400 ; decomposition begins at 450, and between that and 500, it 

 affords the pure protoxide of nitrogen. 



* Ann. de Chim. et de Phys. XVIII, p. 442, and Thenard, III, 265. 



t A few embers, under an earthen dish, are sufficient: hot coals would volatilize 

 and decompose the salt. The common aquafortis need not be diluted. The solu- 

 tion is in a good state to crystallize, when a twitching pellicle forms on the surface, 

 and when a knife blade dipped in the solution and waved in the air is speedily cov- 

 ered with small crystals. 



t Dr. Hope says, that it dissolves at 50, in its own weight of water, and gener- 

 ates 46 of cold. 



