Solutions, strictly defined, are preparations consisting of two or more substances, the particles of which react with one another, or are capable of producing by diffusion a homogeneous mixture (in a gaseous, liquid, or solid state) which cannot be separated into its component parts by, mechanical means. Preparations described in pharmacy as solutions are not necessarily simple solutions. In addition to solutions of definite chemical substances (such as solution of ammonia, solution of ferric oxychloride, or solution of strychnine hydrochloride) this group includes preparations produced by the action of various solvents upon substances of animal or vegetable origin, which cannot be conveniently classed under other headings. Solutions prepared with the same solvent are grouped, according to the solvent employed, in series such as glycerins, spirits, waters, and wines. Galenical preparations, such as decoctions, infusions, and tinctures are not regarded as solutions. They usually contain in addition to definite solutes inert substances in solution or suspension which are indefinite in character.