crystalloid (rus. кристаллоид) — antipode of a colloid, a substance that is easily soluble and crystallising, which, in the dissolved form, can pass through membranes that are permeable to liquids.


The term "crystalloid" was introduced to describe the differences between water-soluble substances in terms of their ability to form true solutions and pass, while in the dissolved form, through vegetable or animal membranes. Some substances percolate much faster than others, which makes it possible to separate them by dialysis. Most salts and acids can crystallise and diffuse quickly (chlorinated metals, magnesium sulphate, hydrochloric acid and arsenous acid), others do not crystallise (soluble silica, gelatin, albumen, caramel, tannin). Representatives of the first group are referred to as crystalloids, and of the second group, colloids.


  • Ivanov Victor V.
  • Shlyakhtin Oleg A.


  1. Crystalloid// Academic Dictionaries and Encyclopedias by F.A. Brokgauz and I. A. Efron. — (reference date: 12.12.2011).