Day: February 20, 2019

Remember the Respirometers? Part I: My Mischief is Unstopp(er)able

Remember the respirometers?  The ones that arrived largely broken or incomplete?  Recently the students did the lab exercise that uses them.   Making things break wasn’t the only fun I had with the respirometers.  Pfft!  I am much more multimischievous than that!

First, the human female and her Prep Staff had to assemble them for use.


A word of explanation:  The respiration experiment measures the gases given off by the germinating beans in one tube, compared to the not-doing-anything that goes on in the tube with the dry beans.  For it all to work, all the components must be air-tight.


When the instruments came from the manufacturer, they had no stoppers at all.  That little goof was immediately obvious, so the professor whose project this experiment is demanded that some be sent.

I helped the manufacturer pick out the stoppers to include, so they sent nice, white ones.  Which all proved to be too small to actually seal the test tubes.  Not only that, but they were made of some weird substance that left chalky dust all over everything.

The professor caught this mistake soon after the white stoppers arrived and demanded that the manufacturer supply stoppers that would actually work.

So the black ones arrived.

Which was all well and good, except that they didn’t have any holes.  Holes are a bit critical for this application, but a pain in the neck to drill, so the professor shipped them all back, saying, “I’m not doing this, YOU do it.”

Let us examine the stoppers which were ultimately received and which the science nerds are using today.

Sturdy.  They appear to be made out of the appropriate type of rubber.


Odd, though.  Every other black rubber stopper she’s ever seen has the size number on the top.  It’s on the bottom of these, so the human female is automatically suspicious.

Not to mention the little stray fringey bits around the edges.  All in all, a substandard molding job.

Thor’s bitty ball-peen!  They are not all the same size, either!


Nor are the holes!  In assembling the respirometers for use, some bits of tubing are going in neatly and sweetly, while some are so hard to insert that the human female and her minions are getting cramped and bruised fingers from trying to jam them all the way in.  Slicking stopper holes up with glycerin isn’t entirely solving the problem–it just makes everything slippery and hard to grip.  Eehehehe!  Sometimes I’m so naughty I crack myself up!

They are partway through the assembly and the human female has just discovered that….TA DA! 


Not all of them are completely drilled!!

See?!  Little pucks of rubber that have to be poked out with a probe or small paintbrush handle.


Uh, oh!  I am laughing so hard I think I may have hurt myself, and Prep Staff is starting to mutter about “acetone” again.

I think I shall beat a strategic retreat.

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