NITRIC ACID 337 



NITRIC ACID 



ACIDUM NITRICUM. Aquafortis. A liquid containing 70 

 per cent, by weight of hydrogen nitrate, HN0 3 , and 30 

 per cent, of water. (B.P.) 



Nitric acid is prepared by the interaction of sulphuric 

 acid and potassium or sodium nitrate. Specific gravity 

 1-42. The B.P. Acidum Nitrieum Dilutum contains 17-44 

 per cent, of hydrogen nitrate. HN0 3 . Specific gravity 

 1-101. 



PROPERTIES. Nitric acid, in tolerably concentrated solu- 

 tion, is colourless ; emits pungent, corrosive, suffocating 

 fumes ; has an intensely sour taste ; oxidises, corrodes, and 

 dissolves many organic substances ; has great affinity for 

 water ; in imperfectly stoppered bottles it quickly increases 

 in quantity and diminishes in strength ; diluted with water 

 it evolves much heat. 



Its tests are the production of an orange-red colour with 

 a solution or crystal of morphine or brucine ; copper, 

 mercury, and some other metals deoxidise strong solutions, 

 with evolution of ruddy nitric peroxide fumes (N0 2 ) ; it 

 gives a yellow stain of picric acid to wool and to the skin 

 a discoloration deepened by alkalies, and removed from the 

 skin only by its desquamation. 



ACTIONS AND USES. Nitric acid is irritant and corrosive, 

 and especially destructive when in concentrated solution 

 and containing the volatile nitrous acid. It leaves yellow or 

 brown stains on the skin and throat, but in the stomach 

 this discoloration is usually obscured by inflammation or 

 extravasation of blood. Besides acting like the other mineral 

 acids, it exerts oxidising effects, notably when used locally, 

 and probably also when given internally. It has some 

 reputation as a hepatic stimulant and tonic, frequently 

 indicated in horses recovering from influenza, jaundice, and 

 other debilitating disorders, and is alternated with arsenic, 

 in eczema and chronic skin diseases, but is not so good for 

 these affections as dilute nitro-hydrochloric acid. 



Externally the medicinal acid is applied for extirpating 

 warts, fungous, and malignant growths which cannot be 



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