Mounted arc tube |Mounted arc tube. | In some ways, gases are a
pain from a sample point of view. With the exception of chlorine
and bromine they all look exactly the same: Like nothing at all.
My beautiful set of noble gas flasks is beautiful because of the
flasks, not what's in them, which is indistinguishable from
plain air or vacuum. (So much so that I got them for a bargain
price because the seller thought the were empty.) But set up an
electric current through almost any gas, and things are
completely different. The current ionizes the gas, and when the
electrons fall back into their orbits, they emit light of very
specific frequencies. These spectral lines can easily be seen
with even a very cheap pocket spectroscope, and they give the
glowing tubes very unusual colors. So unusual in fact that they
are basically impossible to photograph. The pictures here simply
don't look at all like the real colors of these tubes, which
cannot be represented by the limited red, green, and blue
mixtures available in c