| 摘要 |
An apparatus for oscillating a test tube so as to agitate the content thereof, comprises an annular holder from which the test tube can be hung by means of a flange located on the upper end of the test tube, in a manner such that the test tube is restricted swingable outwardly in all directions from its vertical rest position. Mounted externally of the test tube bottom is a plate of soft-magnetic material or a plate-shaped permanent magnet with its magnetic axis coinciding with the axis of the test tube. A plurality of electromagnets for example four in number, are stationarily arranged with their respective first poles located in a common horizontal plane at a distance beneath the lower end of the test tube, in a manner such that the poles lie on a circle concentrical about the vertical rest position of the test tube. The opposite second poles of the electromagnets are connected to a common, soft-magnetic pole piece, and the electromagnets are energized in a predetermined sequence and in predetermined directions, so that as a result of the co-action of said first poles of the electromagnets and the soft-magnetic plate or plate-shaped permanent magnet on the test-tube, the test-tube is caused to effect a nutational rotation about the vertical rest position, with the apex of the nutational rotation located substantially in the center of the annular holder.
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