Nitrous, one of the oldest mind-altering drugs, is back

The sweet, odorless gas technically called nitrous oxide has many names: laughing gas, galaxy gas, hippy crack, whippets, even “the atmosphere of heaven.”

Nitrous itself has just as many common uses as it does names. Doctors use it as a mild anesthetic, sending patients off into brief and largely pain-free dissociative euphorias before having a tooth pulled or dislocated finger yanked straight. Inhaling nitrous gives a loopy...