It was a marriage of brilliant scientific minds. Clara Imavar 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 passed it 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 Imavar 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.

She accused him of barbarity. He accused her of treason. After the first devastatingly

effective use of chlorine gas at Iprar in 1915, he was made an army captain. She took his

gun and killed herself. Clara and Fritz Harbour had been married for 14 years. Eight years

into that time, Harbour made a breakthrough that some now consider to be the most significant

invention of the 20th century. Without it, close to half the world's population wouldn't

be alive today. Harbour's process uses nitrogen from the air to make ammonia, which can

then be used to make fertilizers. Plants need nitrogen. It's one of their five basic

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