NITRIC ACID. 



boiled down to a syrupy consistence, and 

 exposed in a cool place, it crystallizes in 

 long prisms, resembling bundles of nee- 

 dles diverging from a centre. These are 

 soluble, according to Henry, in an equal 

 weight of boiling water, and twice their 

 weight of cold ; soon deliquesce on ex- 

 posure to the air ; and are decomposed 

 at a red heat. Fourcroy says, that cold 

 water dissolves four times its weight, and 

 that its own water of crystallization is suf- 

 ficient to dissolve it at a boiling heat. It is 

 likewise soluble in less than its weight of 

 alcohol. By evaporating the aqueous so- 

 lution to dryness, continuing, the heat till 

 the nitrate fuses, keeping it in this state 

 five or ten minutes, and then pouring it 

 into an iron pot previously heated, we 

 obtain Baldwin's phosphorus. This, which 

 is, perhaps, more properly nitrite of lime, 

 being broken to pieces, and kept in a 

 phial closely stopped, will emit a beauti- 

 ful white light in the dark, after having 

 been exposed some time to the rays of 

 the sun. At present no use is made 



of this salt, except for drying some of 

 the gases by attracting their moisture ; 

 but it might be employed instead of the 

 nitrate of potash for manufacturing aqua 

 fortis. 



The nitrate of ammonia possesses the 

 property of exploding, and being totally 

 decomposed, at the temperature of 600 : 

 whence it acquired the name of nitrum 

 flammans. The readiest mode of prepar- 

 ing it is, by adding carbonate of ammonia 

 to dilute nitric acid till saturation t:skes 

 place. If this solution be evaporated in a 

 heat between 70 and 100, and the eva- 

 poration not carried too far, it crystalli- 

 zes in hexaedral prisms terminating in 

 very acute pyramids ; if the heat rise tr> 

 212 C , it will afford, on cooling, long fibrous 

 silky crystals : if the evaporation be car- 

 ried so far as for the suit to concrete im- 

 mediately on a glass rod by cooling, it will 

 form a compact mass. According to Mr. 

 Davy, these ditt't.r but little from each 

 other, except in the water they comsiin, 

 their component parts being as follows : 



Prismatic} 

 Fibrous ^ 

 Compact 5 



contains C69.5 

 2.o 



C 



ammonia 



water < 8.2 

 5.7 



All these are completely deliquescent, 

 but they differ a little in solubility. Al- 

 cohol at 176 dissolves nearly 90.9 of its 

 own weight. 



The chief use of this salt is for afford- 

 ing nitrous oxide on being decomposed by 

 heat. See nitrous oxide, under the art. 

 GAS. 



Nitrate of Magnesia, magnesian nitre, 

 crystallizes in four-sided rhomboidal 

 prisms, with oblique or truncated sum- 

 mits, and sometimes in bundles of small 

 needles. Its taste is bitter, and very si- 

 milar to that of nitrate of lime, but less 

 pungent. It is fusible, and decomposa- 

 ble by heat, giving out first a little oxygen 

 gas, then nitrous oxide, and lastly nitric 

 acid. It deliquesces slowly. It is solu- 

 ble in an equal weight of cold water, and 

 in but little more hot, so that it is scarce- 

 ly crystallizable but by spontaneous eva- 

 poration. 



The two preceding species are capable 

 of combining into a triple salt, an ammo- 

 niaco-magnesian nitrate, either by uniting 

 the two in solution, or by a partial de- 

 composition of either by means of the 

 base of the other. This is slightly inflam- 

 mable when suddenly heated : and by a 

 lower heat is decomposed, giving out oxy- 

 gen, azote, more water than it contained, 

 nitrous oxide, and nitric acid. The resi- 



duum is pure magnesia. It is disposed 

 to attract moisture from the air, but is 

 much less deliquescent than either of tbc 

 salts that compose it; and requires ele- 

 ven parts of water at CO to dissolve it. 

 Boiling water takes up more, so that it 

 will crystallize by cooling. It consists of 

 78 parts of nitrate of magnesia and 22 of 

 nitrate of ammonia. 



From the activity of the nitric acid as 

 a solvent of earths in analyzation, the ni- 

 trate of glucine is better known than any- 

 other of the salts of this new earth. Its 

 form is either pulverulent, or a tenacious 

 or ductile mass/ Its taste is at first sac- 

 charine, and afterward astringent. It 

 grows soft by exposure to heat, soon 

 melts, its acid is decomposed into oxygen 

 and azote, and its base alone is left be- 

 hind. It is very soluble and very deli- 

 quescent. 



Nitrate, or rather supernUrate, of altr- 

 mine, crystallizes, though with difficulty, 

 in thin, soft, pliable flakes. It is of an 

 austere and acid taste, and reddens blue 

 vegetable colours. It may be formed by 

 dissolving in diluted nitric acid, with the 

 assistance of heat, fresh precipitated alti . 

 mine, well washed but not dried. It is 

 deliquescent, and soluble in a very small 

 poction oi' \Y~Un*. Alcohol dissolves iu 



