External

Nitric acid is more often used as a caustic than the others, for, owing to their great affinity for water, it is difficult to limit the action of sulphuric and phosphoric acids; and the remaining acids are not so powerful as nitric acid. It is employed to destroy warts, condylomata, unhealthy phagedenic sores, cancrum oris, etc. Nitric acid is used as Heller's test for determining the presence of albumin in the urine. At present his process is reversed, i.e., the urine is added to the acid. Glacial acetic acid is used for small warts and corns. If this causes pain it may be diluted. Very dilute solutions are rarely employed for their irritant effects, but at some bathing establishments acid baths are used, but it is not proved that they do any good. Any well-diluted acid, especially sulphuric, may be applied to check slight bleeding, as that of leech-bites, piles, etc. Vinegar can always be obtained; even this should be diluted. In fever the skin is often bathed with vinegar as a refrigerant, and very dilute sulphuric acid is used as a local astringent in the sweating of phthisis.

Internal

Mouth. - As acids damage the teeth they should be taken through a glass tube. Lemon juice or citric acid itself is often used to stimulate the secretion of saliva, and hence allay the thirst of fever patients. Lemonade is a favorite drink for this purpose. Lactic acid has been strongly recommended to dissolve the membrane in diphtheria, but there is no evidence that this treatment benefits the patient. Equal parts of lactic acid and water may be applied with a mop, or a spray of a. strength of 1 to 8 of water may be employed. Very dilute nitric acid has been used for the same purpose. Lactic acid is applied more frequently than any other drug with a brush in tuberculosis of the larynx, and in some cases with good results. It is usual to begin with lactic acid, 2; water, 1; and glycerin, 1. The strength of the solution is increased till at last lactic acid alone is used. Other accessible tuberculous ulcers - as those of the tongue and skin - may be treated in the same way.

Stomach And Intestines

Hydrochloric, and to a less extent nitrohydrochloric acid is of the greatest value in that variety of dyspepsia in which the acidity of the gastric juice is deficient. They should, as already explained, be given some little while after a meal. A very useful stomach mixture consists of diluted nitrohydrochloric acid combined with tincture of nux vomica, and some other stomachic, as compound tincture of gentian. Lactic acid has been used for the same purpose. Acids will often alleviate that form of indigestion in which the patient complains of acid eructations and heartburn. For this purpose they should be given during a meal or before it. They then check the excessive secretion of acid and restrain fermentation. An acid mixture sometimes benefits the indigestion of pregnancy, and small doses of hydrochloric acid may be prescribed during typhoid and other fevers, because the secretion of this acid is much diminished when the temperature is raised. Vinegar is often drunk to reduce obesity, but it only does so because a long course of any acid will set up a mild gastritis, and thus hinder the digestion and absorption of food. Carbonic acid, taken as an effervescing mixture, is a common and very efficacious gastric sedative, beneficial, therefore, in painful dyspepsia and in vomiting. Diluted sulphuric acid may be used as a haemostatic in bleeding from the stomach or intestines, but its action is feeble. It is, however, successful as an astringent in many cases of summer diarrhoea. Nitric and nitrohydrochloric acids, increasing the amount of bile poured into the intestines, are given, and sometimes with much benefit, when it is considered that dyspepsia is due to disordered function of the liver. Diluted sulphuric acid is often taken by workers in lead factories, as it forms an insoluble lead sulphate in the intestine and so prevents absorption of lead.

Remote Effects

The remote effects of salts of citric, tartaric, and acetic acids have already been described (see p. 128). They are due to the increase in the alkalinity of the blood and the urine. Phosphoric acid is often given to weak, sickly, anaemic children with the view of improving the quality of the red blood-corpuscles, and possibly aiding the growth of bones, but it has not been proved to have any great value. The same may be said of lactic and phosphoric acids when given for diabetes; indeed, the latter is said to do harm. There is probably no doubt as to the value of lime and lemon juice in the treatment of scurvy. Lime juice was formerly a popular remedy for acute rheumatism, but it did little if any good. Sulphuric acid is by some said to be anhidrotic in the night-sweating of phthisis, and had some reputation as a remote haemostatic, but it is rarely given now for these purposes. Aromatic sulphuric acid, with a little syrup and water, forms a pleasant cooling drink in fever. Rohrig found that acids diminished the tracheal secretion, and some physicians find that they diminish the secretions in bronchitis. We thus see that the remote effects of all acids, except citric, tartaric, and acetic, are unimportant.

Toxicology

All these acids are severe gastro-intestinal irritants when given in toxic doses. Tartaric, citric, and lactic are very rarely taken as poisons.

Symptoms

These are severe burning pain extending from the mouth to the stomach, excoriation of the mouth with the formation of sloughs, great difficulty in swallowing, vomiting of dark-brown, coffee-colored material and shreds of mucus, intense abdominal pain aggravated by the slightest movement, generally obstinate constipation, but if the bowels are open the motions are dark, from the blood contained in them. Some of the acid generally passes down to the larynx, and causes swelling of that organ and consequently dyspnoea from obstruction to respiration. The patient becomes cold, collapsed and covered with a cold sweat; his pulse is very feeble, and he suffers from great thirst. Post-mortem. - The mucous membrane of the mouth and oesophagus is softened and corroded, and whitish-gray sloughs and haemorrhages may be seen here and there. The coats of the stomach are softened. It is often contracted, and it may be perforated, the aperture being irregular. If the acid escapes into the peritoneal cavity, it may act on almost any of the abdominal organs. Should the patient have lived long enough, there may be corrosion and inflammation of parts of the small intestine. The mucous membrane of the throat and larynx is inflamed and swollen.

Treatment

Alkalies should be given at once, e.g., soap and water, lime water, magnesia, washing soda; and then demulcents, as milk, white of egg, oil, linseed tea. Do not use the stomach tube if sulphuric acid has been taken, otherwise wash out the stomach. Morphine may be injected subcutaneously for the pain, and brandy given subcutaneously for the collapse.