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Q & A: Capillary Tubes

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Most recent answer: 10/22/2007
What is a capillary tube?
- Jer (age 13)
Jer -

A capillary tube is just a REALLY thin tube. (Usually about 1/2 mm across on the inside.) They can be made out of glass, plastic, metal, etc. Glass capillary tubes are probably the most common and are frequently used by biologists and chemists because you can use them for experiments where you only have a very small sample to work with.

One of the things that makes capillary tubes so useful is called ’capillary action.’ Because of this, if you stick the open end of a capillary tube into water, the water will draw itself right up into the tube. Sounds strange? Not that strange. The reason for this is that water really likes to stick to things like glass or plastic. So the water pulls itself up the inside of the plastic, sticking to it like this:

Water pulling itself out of the inside of plastic.

(published on 10/22/2007)

Follow-Up #1: sealing tubes

how is a capillary tube sealed when performing a microhematocrit?
- sofia
A very quick web search for ’microhematocrit’ turns up this phrase:
"Ends can be sealed by flame, sealing clay or patented caps"
You can do that sort of search just by typing the keyword into a standard search engine.
Mike W.

(published on 10/22/2007)

Follow-up on this answer.