Distilled Water

DISTILLED WATER, or distilled, aqua destillata, is obtained by the temporary conversion of water into steam and subsequent cooling, resp. condensation of the steam into water, whereby the water is purified of all inorganic and organic impurities. For medical, pharmaceutical, and chemical or technical practice, it is sufficient to have such distilled water which has been obtained by the distillation of good drinking water from an ordinary copper boiler with a tin or tinned helmet and a similar coil. According to the Pharmacopoeia VII, distilled water must be neutral, transparent, colorless, odorless, and tasteless, with a specific gravity at 4° of 1.000, and must not contain NH₃, Cl, sulfuric acid, nitrous acid, nitric acid, calcium, and other metals and metalloids; furthermore, distilled water must be free from CO₂ and organic substances; upon evaporation of 10 cubic centimeters of distilled water, there should be no residue of more than 0.5 mg. For solutions intended for subcutaneous injection, for eye drops, etc., one should, as a precaution, take distilled water that has been sterilized or boiled. Sterile, completely transparent distilled water is obtained by filtering it through a Berkefeld filter or a Chamberland candle. If, for certain purposes, it is necessary to free distilled water particularly thoroughly and completely from organic substances, one takes good distilled water, adds a small amount of potassium permanganate salt, and distills it from a Jena glass retort with a similar condenser (Liebig) and receiver. However, glass apparatus, just like porcelain, is corroded by water, albeit very weakly, and consequently releases a negligible amount of its constituent parts into the water. Therefore, it is even better to use quartz apparatus for distillation. Good, chemically pure distilled water, approaching absolutely pure water, is obtained by repeated distillation of pure distilled water in platinum or silver retorts with cooling tubes and receivers made of the same metals. The proximity of distilled water and water purified by other methods to absolutely pure water is visible from the following comparison of electrical conductivity values: Conductivity: For absolutely pure water calculated . . 0.038; Water obtained by thawing pure natural ice from the purest natural water . . . . . . . . . . . . . . . 2.130; Water purified by the Nernst method by freezing from distilled water . . . . . 4.800; Water from artificial ice . . . . . . . 137.000; Ordinary distilled water . . . . . . . . . . . 49.000; Water used by Ostwald in his physical-chemical experiments . . . . . . . . 2.130. The extremely high conductivity for water from artificial ice should be explained by the speed and completeness of its solidification, whereby the entire mass freezes and neither salts nor gases are released. Distilled water belongs to the category of very active substances; it removes (leaches) salts from the tissues of the stomach, causing swelling and subsequent death of cells upon prolonged use; it is considered unsuitable for drinking. Distilled water is a hemolytic poison, and therefore it is not recommended to use it in large quantities (without the addition of salts) for intravenous infusions.