H2O=17.96. Source. - Take 1000 volumes of water, distill from a suitable apparatus provided with a block tin or glass condenser, reject the first 100 volumes, which contain volatile impurities, and preserve the next 800 in glass-stoppered bottles, rinsed with hot distilled water immediately before being filled.

Characters

A colorless, limpid liquid, without odor or taste, and perfectly neutral to litmus paper.

Tests

Evaporated in a clean glass capsule on a water bath, no residue should remain. It is not affected by Hydrogen or Ammonium Sulphide (absence of metallic impurities), Ammonium Oxalate (Calcium), Silver Nitrate (Chlorides), Barium Chloride (Sulphates), or Mercuric Chloride (Ammonia), nor should its transparency be affected when mixed with twice its volume of Calcic Hydrate test solution (absence of Carbon Dioxide). In heating to boiling and acidulating with diluted Sulphuric Acid and adding a one-tenth of one per cent. solution of Potassium Permanganate, the color produced is not entirely destroyed by boiling five minutes nor by afterwards setting the vessel aside, well covered, for ten hours (absence of organic or other oxidizable matters). Aqua Destillata is always to be used for making up prescriptions. (116)