On Sat, 21 Feb 2015 17:25:09 -0000, Tim Streater wrote:

In article , Tough Guy no. 1265
wrote:

On Sat, 21 Feb 2015 07:47:09 -0000, harryagain
wrote:


"Tim Watts" wrote in message
...
On 20/02/15 17:05, Tough Guy no. 1265 wrote:
On Fri, 20 Feb 2015 16:26:40 -0000, Brian Gaff
wrote:

What about the trimfones btalite gas filled tube behind the dial?
I can recall being rather appalled back in the 60s when we found my
grandfathers old alarm clock in a drawer, still glowing from dots of
something or other after 10 years. I doubt it would be adangerous
unless you strapped it to yourself for a while though.

You can buy all sorts of luminous stuff nowadays - is there a different
chemical that glows?

Yes

It's not luminous, it's phosphorescent.
https://en.wikipedia.org/wiki/Phosphorescence

No radioactivity involved

Ah. Although they aways say luminous on the product. I guess it's a more
commonly known word.

Luminous covers all of the above; it's more general.

Phosphorescence to me makes me think of fluorescent tubes.

Fluorescent - when a substance absorbs a photon of UV or X-ray and
emits it at a longer (e.g. visible) wavelength.

Phosphorescent - light emitted by a substance without combustion or
perceptible heat e.g. glowworms or fireflies.

Luminous just means something is brighter than you'd expect given the
ambient light. It tells you nothing about how the object is producing
the extra light.

Phosphors in the tube fluoresce then, and not phosphoresce :-)

--
All I ask is a chance to prove that money can't make me happy.