White Vitriol, or Sulphate of Zinc, is an astringent, tonic, and emetic. It is _used externally_ as a collyrium for ophthalmia (See DOMESTIC PHARMACOPEIA, _par. 475 et seq._), and as a detergent for scrofulous ulcers, in the proportion of three grains of the salt to one ounce of water. It is _used internally_ in indigestion, and many other diseases; _but it should not be given unless ordered by a medical man, as it is a poison._