AGGREGATION (from the

See also:

• LAT

Lat. ad, to, gregare, to collect together)  , in physics, a collective term for the forms or states in which matter exists . Three primary " states of aggregation " are recognized—gaseous, liquid and solid . Generally, if a solid be heated to a certain temperature, it melts or fuses, assuming the liquid condition (see FusloN); if the heating be continued the liquid boils and becomes a vapour (see VAPORIZATION) . On the other hand, if a gas be sufficiently cooled and compressed, it liquefies; this transition is treated theoretically in the article CONDENSATION OF GASES, and experimentally in the article LIQUID GASES .