在实验室做完制氧实验后，试管内壁出现黑褐色污物；做完氢气还原氧化铜实验后，试管内总沉积着一层红色铜；洗涤后的玻璃仪器在存放过程中若与保护层铁制件接触一段时间后会附上黄褐色锈迹；木材（煤）干馏后试管内有炭迹。试管内这些化学污迹不清除就成了“一次性”使用试管 After the oxygen production experiment in the laboratory, dark brown dirt appeared on the inner wall of the test tube; after the hydrogen reduction copper oxide experiment was completed, a layer of red copper was deposited in the test tube; the washed glass instrument was stored with the protective layer during storage. After a period of contact with the iron parts, yellow-brown rust marks are attached; after the wood (coal) is distilled, there is carbon traces in the test tubes. The chemical stains in the test tube are not cleared and become “disposable” test tubes.