A metal chemistry includes an amount of chromium weight of between about 9. A data transfer device for transfer of measurement data to an image reconstruction device connected with the stationary part is disposed between the stationary part and the rotatable part. The comparator circuit generates an output voltage according to a difference between a reference voltage and a feedback voltage. On the basis of the amount of the light reaching the photodetecting portion, the drive device judges whether the disk cartridge is in a write-inhibited state. This invention eliminates the need for user intervention for hitting a button such as the I-Scan button for the Philips I-Scan system, which is one of the systems on which the invention can be implemented. The tank mount includes an annular lower flange extending into a lower region of that annular channel to mate with the overlying annular upper flange and trap a flange seal therebetween.