Finding the Viscosity of Pitch

ColdChrist writes "The University of Queensland has a page about a 72-year-old experiment on the fluidity of pitch. There's a webcam where you can try to become the first person ever to see a drop of the pitch fall; eight drops have fallen since 1930 and the ninth is now forming. The experiment 'demonstrates the fluidity and high viscosity of pitch, a derivative of tar once used for waterproofing boats. At room temperature pitch feels solid - even brittle - and can easily be shattered with a blow from a hammer', but it does flow, as the pictures demonstrate." I know this is going to bring up glass comparisons, so we'll head those off: glass is not a fluid.

Comments

Keeps us from getting bored

[tismith]

The experiment is sitting in a glass cabinet just outside one of the lecture theatres used for a lot of first and second year engineering and science lectures.

When I started in first year (1999), the pitch had formed into an interesting drop, and it provided students with a pretty geeky talking point while waiting for lectures to start.

I remember when we went for holidays one year, and came back to find that the drop had fallen! Everyone was a bit pissed (understandably) that it had fallen during uni hols.

Apparently the rate of drop formation is slowing down due to the air conditioning in the building. Or at least thats a rumour circulating around UQ.

Re:Keeps us from getting bored

[richie2000]

And you're telling us that not once, NOT ONCE, in 72 years sitting in plain view in a University milling with students of all sizes, shapes, colours and states of mental health, not once, did first-year students open the glass cabinet and replace the pitch with feces? Not ONCE? Not even a little bit? Pull the other one, mate.

Oh wait, this isn't in the US, is it? Nevermind...

Kelvin's experiments

[Bazzargh]

Lord Kelvin (William Thomson) created an older pitch experiment: one which had a variety of objects lying on a tray of pitch that are slowly sinking in.

Its usually on show in either the Hunterian Museum or the Department of Physics and Astronomy at Glasgow University.

As I recall, this is considered the oldest continuously running scientific experiment, with the exception only of a wheat-breeding experiment in England? (I can't find references on that, just remember it from back in the mists of time)

BTW: it is more fun to watch paint dry - its faster...

Couldn't resist...

[Anonymous Coward]

It is pitch black. You are likely to be eaten by a grue.

Re:The Fluidity of Glass

[flamingmoose]

Q: Is glass solid or liquid?
A: Yes.

Seems like a clear answer to me.

Re: God's experiments

[cioxx]

I'd consider the universe to be the oldest experiment that I know of, or is it just a very elaborate joke?

In reality God is a hacker who rooted the Universe.

So yes, it's a big experiment (read: Honeypot project)

Pitch is used for polishing optics

[goingware]

Telescope makers and opticians use pitch for polishing glass.

I have a page about telescope making that should give you some jumping off points, but I haven't yet got to the polishing stage of the mirror I'm working on.

One reason for using pitch is that you can press a mirror into it and get a very close fit. Another is that if the mirror is not perfectly spherical, the pitch will flex as the mirror moves across it. And finally, the polishing abrasive (ferrous oxide or cerium oxide) will set in the pitch and have a planing action rather than rolling around and chipping little flakes off as in ordinary grinding.

Pitch is nasty stuff to work with. It takes a lot of practice before a novice telescope maker can make a pitch lap they're happy with.

coffee

[Tharsis]

Now THAT's how I like my coffee...