"Tom" wrote in message
...
David (Normandy) wrote:
The kids
were highly impressed with magnesium ribbon burning in pure oxygen -
they were blind for a while with "welders arc eye" but what the hey.

You might know about chemistry, but you know nothing about welding. Arc
Eye (photokeratitis) is a UV burn to the cornea (often confused with the
much worse "flash" which is a UV burn to the retina).

Had you given those children Arc Eye you would have found youself in
court.

Tom

I was using "arc eye" as a grammatical simile, a figure of speech to
describe a flash of light that was so intense it left everyone who was
watching partially blind for several minutes. It is common in chemistry
classes to demonstrate magnesium ribbon burning in normal air (with 20%
oxygen) which is very bright. In fact burning magnesium powder used to be
used as the flash in old plate photography. The flash produced when burning
magnesium in 100% pure oxygen is somewhat more extreme.

David.