刚检验纯度的试管内存在氢气火焰，再用此试管用向下排空气法继续收集氢气前必须用拇指堵住试管口使火焰熄灭以免发生爆炸。刚验纯的试管中存在氢气的火焰可用以下方法验证。把刚做完氢气验纯实验的试管迅速移入水槽中，底部比管口略低，试管日一小半浸入水中（如图所示），让 Just test the purity of the tube there is a hydrogen flame, and then use this test tube to the next row of air method to continue to collect hydrogen must be blocked with a thumb before the test tube mouth to extinguish the flame explosion. The flame of hydrogen gas just tested in a pure test tube can be verified by the following method. The test tube just finished the hydrogen purity test quickly into the sink, the bottom slightly lower than the nozzle, a half immersed in water test tube (as shown), so