  The presence of microparticles (clusters of micron size) of unknown origin in
the volume of water, including highly purified water (bidistilled, deionized),
has been repeatedly demonstrated by various methods of physical analysis.
Various assumptions have been made about the nature of these microparticles,
but none of them has become generally accepted. The review analyzes the
literature data and the results obtained by the authors using optical and
electron scanning microscopes. The composition and phase state of distilled
water deposits at the bottom of glassware after evaporation of free water are
considered. The structure of the microdispersed phase of distilled water and
the mechanism of phase transitions of its components in the process of natural
evaporation, the end products of which are gel-like water and sodium chloride
crystals, are proposed.
