The inorganic acids in common use for their acidity are hydrochloric, phosphoric, and sulphuric. Their dose is 5 minims (0.3 c.c.) well diluted. Each has an official 10 per cent. dilution; but, as shown by the following table, the strong acids are not 10 times as strong as the diluted acids. The relative percentage strengths are as follows:

Hydrochloric acid


per cent.. . .

Diluted hydrochloric acid


per cent.

Phosphoric acid......



Diluted phosphoric acid.....



Sulphuric acid.......



Diluted sulphuric acid......



Nitric acid is official, but not the diluted nitric acid.

Aromatic sulphuric acid (acidum sulphuricum aromaticum) is a 10 per cent. solution (by volume) of sulphuric acid in alcohol flavored with ginger and cinnamon.

Nitrohydrochloric acid (acidum nitrohydrochloricum) is made by acting on 82 parts of hydrochloric acid with 18 parts of nitric acid. A violent reaction takes place, the acids being split up to form nitrosyl chlorides and chlorine. The reactions are:

Hn03 + 3Hci = Noc1 + Cl2 + 2H20 2Hno3 + 6Hc1 = 2Noci2 + Cl2 + 4H2O

There is a slight excess of hydrochloric acid (Amy), so that nitrohydrochloric acid is a liquid containing free hydrochloric acid, free chlorine, and nitrosyl chlorides, the original acids having lost their identity. It is a corrosive liquid with an unpleasant odor. Diluted nitrohydrochloric acid is about one-fourth this strength. It does not keep.


The strong acids are caustic, destroying the cells by the absorption of water, by the neutralization of alkali, and by other destructive chemic changes. Sulphuric acid chars organic matter; nitric acid turns it yellow. The diluted acids induce a reflex flow of saliva. This is especially rich in protein, and serves to take up and neutralize the acid. In the stomach they promote the flow of gastric juice, and secondarily, by their influence in the production of secretin, promote the flow of pancreatic juice and bile.


When a strong acid is swallowed, it causes burning and corrosion of the mouth, throat, esophagus, and stomach. The most corrosive acids are nitric and sulphuric. From poisonous amounts, whether diluted or not, there are the systemic symptoms of acute acidosis, i. e., dyspnea, twitching, convulsions, coma, collapse, and death. Ewing's conclusions from the experimental production of acute acidosis were: It is possible to kill animals by injection of mineral acids or even of organic acids in large quantity, and such animals die with marked reduction in the acid-neutralizing properties of the blood, and with diminished carbon dioxid content sufficient to explain their peculiar dyspnea The urine shows marked excess of ammonia nitrogen and diminution of urea. The autopsy findings indicate death from asphyxia. It must be remembered that the basicity of the blood, that is, its acid neutralizing power, depends not alone on alkalies, but also largely upon protein, urea, and other nitrogenous substances (Ewing). Fischer finds acids a cause of urticaria and angioneurotic edema.


(A) Local

The local antidotes in the alimentary tract are mild alkalies, such as soap, lime, and magnesia. The carbonated alkalies, such as chalk, sodium carbonate, and sodium bicarbonate, must be used with great caution, if at all, for with the acid they liberate Co2 gas, and this may result in collapse from sudden distention of the stomach or rupture of the corroded stomach wall.

(B) Systemic

To combat the acidosis half an ounce of sodium bicarbonate dissolved in one to two pints of hot water may be given slowly by rectum; or a 3.5 per cent. solution of sodium carbonate may be administered intravenously (von Noorden). In chronic acidosis the administration of proteins, and especially of amino-acids to furnish Nh3, the natural antidote to acid excess, has been tried, without great success. The administration of carbohydrates has been of more value.


Nitric acid is occasionally used for the destruction of warts or small nevi. It causes pain, and often leaves a scar. Its stains of the skin are yellow and indelible. Being a powerful coagulant of albumin, it is not an aid to digestion.

Hydrochloric acid is sometimes employed when the natural acid of the gastric juice is deficient or absent. It is then given in amounts of 5-10 minims (0.3-0.7 c.c.) in a glass of water to be drunk during the meal. The throat will not stand a stronger solution. This may be repeated in half or one hour. It is believed by some that in these cases the acid serves as an antiseptic to prevent the development of gas-forming organisms in the stomach and the passage of putrefactive bacteria into the intestines. There is some good evidence against this belief. Rehfuss (1917) finds that these amounts have no perceptible effect on the gastric chemistry, though apparently useful in some cases in overcoming the diarrhea of achylia gastrica. A great disadvantage from the long-continued administration of mineral acids is the increased elimination of the alkaline bases, with the development of a comparative acidosis. The diluted hydrochloric acid, it will be noted, is about one-third the strength of the undiluted.

Oxyntin, a protein compound of hydrochloric acid, and betaine hydrochloride under the name of acidol, have been introduced for. the administration of hydrochloric acid in solid form. Acidol is strongly acid to the taste. It is claimed that 10 grains (0.7 gm.) of oxyntin represent 5 minims (0.3 c.c.), and 10 grains of acidol represent 7.5 minims (0.5 c.c.) of hydrochloric acid (U. S. P.). In a careful research, Long (1915) found that betaine hydrochloride became dissociated, and its action was almost equal to that of dilute hydrochloric acid of the same concentration. On the other hand, Long found that mixtures made by combining hydrochloric acid with protein, e. g., oxyntin, hold scarcely enough acid to digest themselves.

Dilute nitric, nitrohydrochloric, and phosphoric acids are sometimes employed for the same purpose as hydrochloric. There is no reason for preferring them to hydrochloric, which is the natural acid of the gastric juice; and, as noted above, nitrohydrochloric is an irritant chlorine preparation.

Sulphuric acid, both internally, in dose of 5 minims (0.3 c.c.), and externally, has been employed for the night-sweats of tuberculosis. In the author's experience it is of no value. It was formerly the custom to employ diluted sulphuric acid or aromatic sulphuric acid to bring quinine-sulphate into solution, but since it does so by changing the insoluble sulphate to the soluble bisul-phate, it would be better to use the bisulphate at the outset and avoid employing an arbitrary amount of acid.