A cassette for vaporization of anesthetic agent for delivery to a patient is arranged to be received by an anesthesia machine which has control mechanisms for controlling vaporization of the agent. In a preferred arrangement, the cassette includes a housing for receiving, containing and emitting anesthetic agent. A sensor, such as a pressure sensor or a temperature sensor is embedded in the housing for obtaining a value of the agent contained in the reservoir. The sensor is operatively connected to the reservoir to obtain an accurate value of the agent. A communication link is provided between the sensor and the control mechanisms of the anesthesia machine when the cassette is received by the anesthesia machine. The cassette thus provides a simplified arrangement that efficiently and accurately provides values of the anesthetic agent being vaporized in the reservoir.