In the formal language of economics, X and Y are substitutes if the demand for X increases when the price of Y increases, or a positive cross elasticity of demand.
Potting mix is the material that goes into a garden pot before you put seeds and plants into it. 1  It keeps the plant in place. 2  It holds water for the plantâs roots to soak up.  It contains nutrients that feed the plant.
Pipe Tobacco Mixtures. Mixture is a term often seen on pipe tobacco packages. As the name implies, it is simply a mix of different tobacco types, cuts and flavors. Many mixtures are composed from both loose cut and rubbed tobacco. They are easy to fill and smoke, and have greater robustness and taste variety than loose cut tobacco on its own.