Muriatic acid is an energetic caustic, but les9 so than either of the preceding, as its chemical reactions with the tissues are not so powerful. It has been used to denude the cuticle, and as an application to pseudomembranous exudations in the mouth and fauces, in which it was highly esteemed by Bretonneau, though now superseded by nitrate of silver. It has also been used in ulcers of the mouth, especially those denominated cancrum oris. Diluted, it is used as a gargle in the sore-throat of malignant scarlet fever. For this purpose, one or two fluidrachms may be added to half a pint of water. An objection to this and other acid gargles is, that they are liable to injure the teeth.