This long glass thing here is a burette.

这个长玻璃的东西是滴定管。

And what I'm doing right now, is I'm actually adding less than a drop at a time by going quickly past the opening in this little burette thing.

而我现在正在做的是，我实际上是通过快速通过这个小滴定管的开口，一次添加不到一滴。

It'll stay blueish in color for as long as the bicarbonate ions are around to keep the pH buffered above the indicators end point of pH 4. This long glass thing here is a burette.

只要碳酸氢根离子在周围以保持 pH 值缓冲在 pH 值 4 的指示剂终点之上，它就会保持蓝色。这里的这个长玻璃东西是滴定管。