Therapeutics. Externally it acts as a powerful caustic, and acrid poison. Internally, in a dilute form, as a refrigerant, tonic, and astringent. It is given in some forms of atonic dyspepsia, in low states of the system, as in the petechial form of exanthema-tous diseases. It is also used as a gargle in ulceration of the throat, and in diphtheria.

Dose. Of acidum hydrbchloricum dilutum, 10 min. to 30 min. diluted freely.

Adulteration. Sulphuric acid, chlorine, and iron, for which the tests are given. The commercial acid is generally coloured from the presence of the latter impurities.