NITRIC ACID, Medical Properties of. This acid iu a concentrated form acts as a violent corrosive poison, and is therefore never used in an undiluted state for internal administration, but is sometimes applied externally, when the object is to effect the speedy destruction of any part. Nitric acid however, from its frequent employment in the arts, is often the cause of accidental, rarely of intentional, poisoning, and it surpasses all the other mineral acids in the rapidity of its action, and in the consequent necessity for prompt and judicious treatment. It may be determined to have been the poisoning agent by its causing the parts which it has touched to be at first white, but soon after of a yellowish colour, which cannot be removed, like the stain of iodine, by adding caustic potass, but on the contrary becomes orange on the addition of an alkali or soap. (Pereira.) When it has been taken internally, the lining membrane of the month also peels off iu a state resembling parchment.. The most appropriate antidotes are such sub stances as combine with and neutralise the acid : chalk or magnesia, made into paste with water—or, if these are not at hand, the plaster of the apartment, bruised down and drank—will answer best. " While those are preparing, the acid should be diluted by the free use of any mild fluid, milk or oleaginous matter being preferred. The carbonates of the alkalies are by no means eligible antidotes, as the resulting compounds themselves possess corrosive properties." (Christison.) A solution of soap may be administered, though some object to it from the presence of the alkali in it, but apparently without sufficient ground. If recovery should take Ouse, the individual long suffers from indiges tion, and is almost always constipated.
In an undiluted form, nitric acid is a most valuable application to sloughing pliagedenio ulcers; also for destroying warts; ; for the de struction of Liemorrhoidal tumours (see observations on this subject by Henry Lee, London, 1848); or causing vesication over the stomach in Asiatic cholera, or for dropping into a carious tooth to relieve tooth ache. For all other purposes it is very largely diluted.
In its action on the system it differs from other acids, inasmuch as it does not produce the cooling and thirst-allaying effect which they do, but on the contrary causes a feeling of warmth in the stomach, with thirst and increase of appetite. The use of it continued for some
time gives rise to general effects ; an excitement is felt through the whole system ; the pulse becomes quick, the exhalation great ; and an increased secretion from the salivary glauds, mucous membmues, the liver, and kidneys is manifest. Perseverance in the use of this agent however at last produces many bad consequences ; and in persons much disposed to bleeding from the lungs, it almost invariably causes such bleeding to occur, as well as heat in the chest and obstinate cough. Very largely diluted, it furnishes one of the best drinks in fevers accompanied with great prostration of strength.
It is also a very excellent tonic in many cases, and seems to form the best substitute for the bile where that secretion is scanty. That it greatly augments the secretion of bile, the nature of the evacuations abundantly proves. Hence it differs from almost all other tonics in not causing constipation, but rather the contrary. In calculous diseases of the phosphatic diathesis it has been used with great benefit; and also, very largely diluted, it has been injected into the bladder as a direct solvent. [Lirnossruturries.] In the treatment of scrofula it is a most valuable remedy, but its use must be every now and then suspended, owing to the effects which it produces on the stomach. During its use, care must be taken to protect the teeth, by instantly rinsing the mouth.
It has been regarded as a substitute for mercury in some cases, especially as it promotes the secretion of saliva. It ought never to be given at the same time as mercury, nor even soon after a dose of any mercurial preparatiou, since a poisonous nitrate of mercury may be formed in the stomach. Lastly, nitric acid increases the efficacy of many other medicines, such as ammoniacum, cusparia, and opium.
Nitric acid in the form of vapour was formerly employed as a dis infecting agent, but it is now almost disused. The vapour must be carefully avoided, as the inhalation is very deleterious.
Nitric acid in combination with hydrochloric acid, added to a largo quantity of water, has been used as a bath in chronic diseases of the liver, particularly in India, but it does not seem entitled to much credit.
Nitro-hydrochloric acid is a most valuable tonic in some forms of indigestion and debility, in combination with bitters.