In order to treat liquid or gaseous hydrocarbons easily like solid materials, and to return back to original hydrocarbons at any time necessary, composites of liquid or gaseous hydrocarbons with small amounts of sodium carboxylate are produced. Two methods are adopted. The first method is called the Aggregate Formation Method. Hydrocarbon, sodium carboxylate and pure water are put into a vessel. They are heated and dissolved completely, and cooled gradually. Then, a solidified aggregate of hydrocarbon and sodium carboxylate separates from the water. The second method is called the Long Fiber Method. Sodium carboxylate is dissolved in pure water by heating together in a vessel and then the solution is cooled gradually. In some cases, NaCl is also added. Very long, thin, white fibers of sodium carboxylate are formed in water. As the fibers are very long and thin, all water existing is caught by the fibers. Then at room temperature, hydrocarbon is added. Every kind of the hydrocarbon added is caught by the fiber, and a gigantic solid white ball separates from the water. These two methods apparently differ greatly from each other. However, both depend upon the same principle, namely, intermolecular van der Waals forces between long alkyl chains of sodium carboxylates and hydrocarbon molecules in water play a decisive role in solidifying the adduct.