Methylene blue is widely used as redox indicator in analytical chemistry. In an oxidizing environment the solutions of this substance are blue, if exposed to a reducing agent it will turn colourless. The redox properties can be seen in a classical demonstration of chemical kinetics in general chemistry, the "blue bottle" experiment. Typically, a solution is made of dextrose, methylene blue, and sodium hydroxide. Upon shaking the bottle, oxygen oxidizes methylene blue, and the solution turns blue. The dextrose will gradually reduce the methylene blue to its colourless, reduced form. Hence, when the dissolved oxygen is entirely consumed, the solution will turn colourless.