The term pH stands for the potential (p) of the hydrogen ion (H+) in water. It is actually a way of reporting the concentration of H+ in solution using an electrical "potential" to measure H+. The pH of any solution is one of the easiest laboratory measurements to make using a pH meter and an electrode specifically designed to measure hydrogen (pH electrode). Color indicators and litmus paper are a quick alternative for less precise measurements. By mixing a quantity of soil with demineralized or distilled water (usually a 1:1 mixture), we can measure the pH of the water solution in equilibrium with the soil.