This is the BBC.

As a special Christmas treat, we're giving you an extra program on our podcast feed.

Tim Harford has been working on another series called 50 Things that Made the Modern Economy,

which has been going out on the BBC World Service.

Here's one about the Harbour Bosch process

and its impact on agriculture.

If you enjoy it, there are more episodes on the 50 Things

podcast. 50 things that made the modern economy.

It was a marriage of brilliant scientific minds.

Clara Imovar had just become the first woman in Germany to receive a doctorate in chemistry.

That took perseverance. Women couldn't study at the University of Breslau, so she asked each lecturer

individually for permission to observe their lessons as a guest. Then she pestered to be allowed

to sit the exam. The dean awarding her doctorate said

science welcomes each person irrespective of gender. He then undermined this noble sentiment by observing that a woman's duty was family, and he hoped this wasn't the dawn of a new era.

Clara saw no reason why getting married should interfere with her career. She was disappointed.

Her husband turned out to be more interested in a dinner party hostess than a professional

equal. She gave some lectures but soon became discouraged when she learned that everyone assumed her husband had written them for her.

Reluctantly, resentfully, she let her professional ambitions slide. We'll never know what Clara Imovar might have achieved

had attitudes to gender been different in early 20th century Germany, but we can guess what she wouldn't have done. She would not, as her

husband did, have pioneered chemical weapons. To help Germany win the First World War,

he enthusiastically advocated gassing allied troops with

chlorine.

...