15-18 facts

15. The Romans used human urine as mouthwash.

16. In 1788 the Austrian army attacked itself and lost 10,000 men. 

17. Before becoming pope, Pius II wrote a popular erotic book, The Tale of Two Lovers. 

18. People were buried alive so often in the 19th century that inventors patented safety coffins that would give the "dead" the ability to alert those above ground if they were still alive.