A vessel (1) for the mixing of fluid substances (4) is provided, which is fully lined on the inside with synthetic enamel or the like and which includes a main body (2), a lid (3) for the main body, a stirrer (5) inside the main body (2), and a multiplicity of additional devices (12, 15) for controlling and monitoring the substance mixture, characterized in that it has a multiplicity of support elements (13) for the multiplicity of additional devices (12, 15), which are integrally mounted on the inner surfaces of the main body and are likewise fully coated, each support element (13) being suitable for removable mounting of the respective additional device of the multiplicity of additional devices (12, 15) inside the main body (2).