方法一 :取盛医药用的塑料 (自身材料密度比水小 )小药瓶 ,容积约三四十毫升 ,丢掉瓶盖。先放入水中浸泡 ,使自身密度不再改变 ;把细黄砂先放入器皿中用水泡上 ,使自身密度不再改变。然后往小塑料瓶中加入少许黄砂 ,瓶中亦装满水 ,使瓶直立浮于水中。接着用角匙多次加微量细砂 Method one: Take Sheng Pharmaceutical’s plastic (smaller than its own material density) small medicine bottle, the volume of about 30 ml, lose the cap. First soaked in water, so that their density no longer changes; put the yellow sand first into the vessel with water, so that their density no longer changes. Then add a little yellow sand to the small plastic bottle. The bottle is also filled with water so that the bottle stands upright and floats in the water. Then use the angle spoon to add traces of fine sand several times