Surfactant Surfactant Surfactants are compounds that lower the surface tension (or interfacial tension) between two liquids, between a gas and a liquid, or between a liquid and a solid. Surfactants may act as detergents, wetting agents, emulsifiers, foaming agents, and dispersants. The term "surfactant" is a blend of "surface active agent". In the United States National Library of Medicine's Medical Subject Headings (MeSH) vocabulary, "surfactant" is reserved for the meaning pulmonary surfactant. For the more general meaning, "surface active agent/s" is the heading. Surfactants are usually organic compounds that are amphiphilic, meaning they contain both hydrophobic groups (their "tails") and hydrophilic
Drop (liquid) Drop (liquid) A drop or droplet is a small column of liquid, bounded completely or almost completely by free surfaces. A drop may form when liquid accumulates at the lower end of a tube or other surface boundary, producing a hanging drop called a pendant drop. Drops may also be formed by the condensation of a vapor or by atomization of a larger mass of liquid. Liquid forms drops because the liquid exhibits surface tension. A simple way to form a drop is to allow liquid to flow slowly from the lower end of a vertical tube of small diameter.