September - 20 years ago; 75 years ago; 130 years ago; 175 years ago; 250 years ago
20 years ago
DNA fingerprinting discovered by British geneticist Sir Alec Jeffreys. The technique is now widely used in legal medicine to establish identity. Jeffreys was awarded the 2004 Louis-Jeantet prize for medicine.
75 years ago
John Lennard-Jones, British chemist, presented The linear combination of atomic orbitals molecular orbital method, used in quantum chemistry. Knighted in 1946, Lennard-Jones held the UK’s first chair of theoretical chemistry.
130 years ago
Dutch chemist, Jacobus van’t Hoff proposed a tetrahedral geometry for carbon. His proposal, based on experimental evidence not direct observation, was strongly criticised as ’fancy trifles.devoid of factual reality’. In 1901 he went on to receive the first Nobel prize for chemistry.
175 years ago
Organic chemist, Friedrich August Kekul? von Stradonitz, was born in Germany. Reportedly, the ring solution to the structure of benzene came to him in a dream of a snake eating its own tail. However, it is said that his solution to the problem of how carbon atoms could bond to up to four other atoms at a time was dependent on Archibald Scott Couper’s previous work.
250 years ago
French chemist, Joseph-Louis Proust was born. Proust made one of modern chemistry’s fundamental observations: the law of definite proportions. He mixed elements like tin and iron with oxygen, revealing that they combined in fixed proportions, a controversial and widely disputed finding.