| 摘要 |
<p>The device comprises a slide which in the rest position has one hole part located under the stack of beakers, and has a peripheral flange of such dia. that passage of a beaker is not possible. In its work position, the slide has its other hole part beneath the beaker stack. The upper part of this hole has a dia. preventing passage through the hole, whilst the lower part of the hole has a dia. permitting a beaker to pass.</p> |
