In the age before warning labels and liability waivers, scientific experimentation often looked like something between a séance and a rave. Case in point: this glorious 1807 illustration from a ...

Nitrous oxide (laughing gas) has been used as an anesthetic in medicine and dentistry for 150 years. In this illustration from a 19th century book, a man is shown dancing after inhaling the gas.

ILLUSTRATION: Getty Images ... Laughing at work can seriously help your career. When former corporate sales executive Betty-Ann Heggie first laughed loudly at a work dinner a few years ago, ...