THOSE SILLY LITTLE HALF-REMEMBERED THINGS

I quite often get sent emails warning me about this and that, and, like most people I suppose, I either dismiss them as so much spam or cursorily read them through to see how relevant they might be to me and mine, before either deleting them immediately or filing them away for future deletion.

Occasionally, I will go a-rummaging through that list of old emails just to see if there’s anything really worth keeping but, in general, most of those messages fall into the rather broad spectrum of being regarded as “junk”.

My mind is full of enough junk as it is, and I’ve started reaching an age where there are myriad slightly fascinating facts spinning around what’s left of my supply of braincells and I will occasionally remember them without having the faintest idea of their source or provenance, usually falling back on the old faithful “I think I read somewhere that…” which is difficult to follow up when you simply don’t have a clue where it was that you actually read it and, more importantly, what many of the salient points were.

For example, we were recently having a conversation about microwaving drinks in the kitchen at work, when I happened to remark as to whether the person put a wooden spoon into the mug for safety reasons.

Naturally, this strange seeming suggestion was questioned and I had to mutter something about reading somewhere about liquids getting superheated in microwave ovens if there wasn’t some kind of flaw in the receptacle, and the spoon being suggested as a way of breaking the surface tension.

Or something.

The problem was that I really couldn’t remember many (or even any) of the details. I know that I once got one of those alarming “warning” emails about it a few years ago, but then, like many of us do, I promptly forgot all about it.

Anyway, it turns out that I was (sort of) right, and the person I was having the conversation with sent me back the email quoted below which is just the kind of useful information that is quite useful to know, so I thought I’d better just drop it in here as another gentle reminder instead of providing yet another source of spam for the whole world to tut over before deleting it. After all, to a lot of scientists, it probably all seems “blindingly” obvious, if that’s not too dark a pun under the circumstances.

General Electric's response: Microwaved water and other liquids do not always bubble when they reach the boiling point. They can actually get superheated and not bubble at all. The superheated liquid will bubble up out of the cup when it is moved or when something like a spoon or tea bag is put into it. To prevent this from happening and causing injury, do not heat any liquid for more than two minutes per cup. After heating, let the cup stand in the microwave for thirty seconds before moving it or adding anything into it.

Here is what a science teacher had to say on the matter: "Thanks for the microwave warning. I have seen this happen before. It is caused by a phenomenon known as super heating. It can occur anytime water is heated and will particularly occur if the vessel that the water is heated in is new, or when heating a small amount of water (less than half a cup). What happens is that the water heats faster than the vapor bubbles can form. If
the cup is very new then it is unlikely to have small surface scratches inside it that provide a place for the bubbles to form. As the bubbles cannot form and release some of the heat that has built up, the liquid does not boil, and the liquid continues to heat up well past its boiling point.
What then usually happens is that the liquid is bumped or jarred, which is just enough of a shock to cause the bubbles to rapidly form and expel the hot liquid.
If you pass this on ... you could very well save someone from a lot of pain and suffering.”

Strangely it all relates in another small way to that other fascinating fact about champagne bubbles that I know that I know about, but then always seem to forget that I do know. You know, that tired old chestnut that sometimes gets pulled out of the bag at weddings, that the bubbles only form because there are flaws in the glass for them to form on.

Maybe I’ve been sitting with some very strange people at the weddings I’ve been to…

Still, it’s those very same flaws that prevent our hot coffee from exploding in our faces as we get it out of the microwave. Perhaps the observation about champagne only gets trotted out at weddings because, for most of us, that’s our only regular contact with the old shampoo, although I’ll accept we could just be talking about antisocial old me there, with my lifestyle being slightly more P.G. Tips than Moet et Chandon.

Anyway, be careful with your hot liquids, my friends. If you take nothing else away from these thoughts, just try to remember that one.

Now there was something else I read somewhere. Something about flushing the loo with the lid down because it reduces the spread of germs.  I think I read that in Bill Bryson’s book “At Home” but I’d have to look it up…