Richard Wilhelm Heinrich Abegg (1869 – 1910) was a German chemist and pioneer of valence theory. Because of his research he proposed that the difference of the maximum positive and negative valence of an element tends to be eight. This has become to be called Abegg's rule. He was a gas balloon enthusiast and this is what caused his death at the age of 41 when he crashed in his balloon Schlesien. 1869 (MDCCCLXIX) is a common year starting on Friday (link will take you to calendar) of the Gregorian calendar or a common year starting on Sunday of the 12-day-slower Julian calendar. ... 1910 (MCMX) was a common year starting on Saturday (see link for calendar) of the Gregorian calendar or a common year starting on Sunday of the 13-day slower Julian calendar. ... A chemist pours from a Florence flask. ... Valence is a scientific term in chemistry to describe electrons in the outermost orbital. ...