Abstract: In a thermogravimetric apparatus which is composed of a balance-arm 1, a detector 2 for detecting an amount of deviation of the balance-arm 1, a control circuit 3 for controlling equilibrium of the balance, and a driving part 6 for moving the balance-arm to the balanced position, vibration of the balance-arm has been made possible by adding a vibration generating circuit 5 for vibrating the balance-arm 1 and an adding circuit 4 for adding a signal from the control circuit 3 to a signal from the vibration generating circuit 5. A measurement which is excellent in reproducibility and accuracy is thus obtained. Automation of replacement of samples and unattended measurement are also made possible.

Abstract: An aquarium filter of the free standing, nesting type is provided with an improved magnetic coupling system to couple a drive motor to the impeller which pumps water through the filter. A ring-shaped magnet is secured to the motor shaft and a second magnet coupled to the impeller and carried within the filter housing is inserted into the space inside the first magnet. The magnets are maintained coplanar and the rotation of the motor is coupled to the pump impeller of the filter in a very efficient fashion.