The Alchemy of Air by Thomas Hager: In the early 1900s, the German chemists Fritz Haber and Carl Bosch staved off global starvation by turning nitrogen from the air into fertilizer for crops. Their explosive discovery fed millions, but it also kick-started the chemical weapons industry and helped fuel Hitler’s rise to power. This scientific adventure spans two world wars and every cell in your body: About half the nitrogen in every human being today originated in a Haber-Bosch factory.