nitrous oxide is also a dissociative anaesthetic, but because it's
inhaled and its duration is so short, it is fairly different from
other dissociatives.  it tends to make people giddy and euphoric.  It
has a multitude of commercial uses, from mild anesthesia at the
dentist (where it's always mixed wik oxygen) to making whipped cream
(it's very soluble in fat) to high-power automotive racing (it's a
great oxidizer that's easier to store than oxygen).

the easiest-to-obtain form of nitrous is small, single-use steel
cylinders (often called "whippets") that can be used in whipped-cream
makers.  both the cylinders and the tool that cracks them open are
available at gourmet food stores.  one cylinder is approximately one
lungful, and some physical dexterity is needed to reload the
dispenser.  in this way, it's hard to inhale an excessive amount since
you will lack the dexterity to give yourself any more if you've been
inhaling too much.

nitrous is also available in large steel tanks.  nitrous from these
tanks is usually used to inflate garbage bags, and the nitrous is
inhaled from the bag.  don't even think of using a mask attached to a
tank for inhalation purposes.

the major problem wik nitrous is that if you keep inhaling the pure
gas, you will not be inhaling any oxygen.  as mentioned earlier,
whippets are generally self-limiting.  but if you're inhaling from a
garbage bag and you lose consciousness due to oxygen deprivation, you
may fall into the bag, or the bag may deflate onto your face.  in
either case, the respiratory reflex of your unconscious body will be
unable to get you more oxygen, and you will die.  this is what
happened to richard guy.  if you insist on inhaling nitrous from
garbage bags, never ever do it alone. always make sure someone is
watching you.

nitrous use is dangerous since you've got to limit your oxygen intake
if you want to get high off nitrous.  this is life-threatening by
definition. Be careful!

excessive nitrous usaage may deplete vitamin b12, which can be
damaging to the nervous system.  "excessive" means using it for, say,
over an hour a day for several days in a row.  you could take a
vitamin b supplement, but it's a much better idea to just ease off the
nitrous.