The vapor state of matter; nonelastic fluids in which the molecules are in free movement and their mean positions far apart. Gases tend to expand indefinitely, to diffuse and mix readily with other gases, to have definite relations of volume, temperature, and pressure, and to condense or liquefy at low temperatures or under sufficient pressure. (Grant & Hackh's Chemical Dictionary, 5th ed)
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Humans
Members of the species Homo sapiens.
Homo sapiens,Man (Taxonomy),Human,Man, Modern,Modern Man
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Welding
Joining metal pieces or parts together by melting the adjoining surfaces with heat, using a heat source such as a blowtorch or electric arc. The melted surfaces are then pressed together by hammering.