Abstract: A spraying apparatus having a sprayer head and an interchangeable cartridge that can dilute and dispense a chemical is disclosed. A first fluid entering the sprayer head mixes with a second fluid that is drawn from the cartridge by aspiration to dilute the second fluid and the mixture is dispensed. The cartridge has an upper cap plate and a cap lid that rotate or slide with respect to each other, to allow easy installation and use, and safe storage of the cartridge for subsequent use. A rotatable valve can permit filling of the cartridge to a pre-selected degree of dilution.