Day: February 21, 2019

Remember the Respirometers? Part II: I Called It

Did you think the stoppers were the only bits of the respirometers I worked my mischief on?  Pfft!  It’s like you don’t even know me!


As I predicted, it was a fiasco.  Admittedly, the prediction doesn’t count, because I contributed to the fiasco, but that does not diminish the fun I had watching the human female and her minions scurry, struggle and curse.

First the cantankerous instruments got filled with a small amount of bluish-purple indicator fluid–a simple mix of glycerol and dye.  Never mind the fussy business of getting it equal in all the various tubes, I saw to it that it kept making air bubbles (which interferes with getting a reading) and that the students let their reactions go too long, letting the fluid go up and over into the dry beans or the live, respiring beans.  The Prep Staff was kept hopping, replacing wasted fluid in all the rooms all the time.

And the fluid was wet enough to wake the dry beans up and start respiring, which played merry Hel with the results.

Then there were the test tubes.  They were filled with a bit of cotton, a plastic platform (just visible in the left of the picture below), and then either dry beans or soaked, living beans.


I had a hand in choosing the platforms for the respirometers.  I made sure that they weren’t all exactly alike.  Some were just a smidge larger in diameter.  Prep staff broke four tubes just loading the platforms in.  The students broke a further five by pressing too hard, trying to jam the rubber stoppers in.  Prep staff spent all week cannibalizing spare units for parts.

Then there were the bits of tubing.  The rigid ones turned out to be plastic,  not glass, but you know what?  They break just as easily!


*Tink!*  Just like that.  We went through a lot of those.

Unfortunately, the human female put on her Science Thinking Cap and there may be work-arounds for next semester.


A plastic 50-milliliter graduated cylinder is going to fit as a replacement for the test tubes.  The rig is even more stable afterwards, as the cylinders have big “feet.”  Prep Staff will probably have to cut them all off below the spout so the stoppers will fit, though.

And the breaky little graduated tubes?  Close inspection shows that they are cut from 1-milliliter plastic serological pipettes.


The human female discovered a five-kilo box of the things in a storage cupboard in one of the prep rooms.  They’ll have to cut those to fit, too.

In short, they can actually improve the basic apparatus!

Am I discouraged?  Disheartened?  Hel, no!  They’ll probably try to use a Dremel motorized cutting tool to do both modifications, and no one ever uses one of those without a mishap or three.  It’ll be broken cutting wheels, sharp edges, slips, sparks, and that annoying, high-pitched “nnnnnyeh, nnnnyeh, nnnnnnyeh” noise that’ll give everyone a screaming headache.

I can work with that.

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