I have seen these small test tube looking doohickeys being supplied from many chinese suppliers, but never with any description as to what they are for. They almost invariably have the description "Automatic Filling Tube Liquid Test Tube With Spout" which didn't lead me anywhere.

With most glassware, even relatively complex pieces, I can usually discern what it is for and why it is designed in that way but this has me stumped. My best guess so far is that it is meant to collect liquid from a sealed flask where the long stem passes through a bung to the bottom of the flask and gas pressure pushes some liquid up and into the tube. So maybe it is for volumetric reagent dispensing? If you had a squeeze bulb on the bottle it would push liquid up into the tube, then suck back and reduce the level to a consistent volume, but you would have to tip the whole bottle to pour it out so idk?

If anyone is familiar with what these are for and how they are used it would be much appreciated because this has been bothering me for a while.

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    $\begingroup$ I had several of them and I never figure out. I think what you and they say might be the purpose. Nothing too volumetric, though. Just I don't see the type of sealing that the long stem can easily and practically go through without loosing the sealing itself. $\endgroup$
    – Alchimista
    Nov 15, 2020 at 8:51
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    $\begingroup$ @Alchimista. I agree. This technique is not perfectly volumetric. It is used when an order of magnitude on the result is considered as satisfying. It is often the case in waste water treatment plants. And if the punched rubber stopper is leaking, it is replaced. $\endgroup$
    – Maurice
    Nov 15, 2020 at 17:54
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    $\begingroup$ Ah, thanks. I wonder if they were used with some sort of air pump like a squeezable bulb on a separate hole on the bung, or if there is there some way to tip the whole bottle so that it fills? With the little angled tube inside it looks like you could get accuracy around 0.5mL if it sucks back the excess. Either way it's a clever method of getting rough volumetric dispensing without moving parts. $\endgroup$
    – TWiz
    Nov 16, 2020 at 4:54

1 Answer 1


It is an apparatus for taking a sample of a liquid from a big container. Let's suppose you have at your disposal a big bottle (at least one liter) which has two holes on a level with one another at middle height. Now imagine that a flow of a small river is entering the bottle from the upper neck, at such a rate that the level of the water inside is always on a level with the holes. The water gets out through the lateral holes. Now you put a punched rubber stopper in one of these holes. And the long thin pipe of your glassware is horizontally inserted into the stopper hole. Your glassware can then be turned and placed in such a way that the broader tube is vertical with its neck above. With this equipment, the broad tube is all the time half-filled with water. If the composition of the water slowly changes, a sample of its composition may be taken by turning the broad tube so as to empty it upside down, then putting it vertically again.

  • $\begingroup$ Indeed I've found them among dismissed glassware at a water waste treatment plant. $\endgroup$
    – Alchimista
    Nov 15, 2020 at 11:50

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