The Science Book

159 with a microscope. He found it to be teeming with the type of microbes that had been linked with the decay and spoilage of f ...

ONE OF THE SNAKES GRABBED ITS OWN TAIL AUGUST KEKULÉ (1829 –1896) ...

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162 AUGUST KEKULÉ T he early years of the 19th century saw huge developments in chemistry that fundamentally changed the scienti ...

A CENTURY OF PROGRESS 163 Kekulé used the concept of valency to describe the bonds that are formed between atoms to make various ...

164 AUGUST KEKULÉ linear structure that was not highly reactive was a real conundrum. There clearly had to be double bonds, but ...

165 are delocalized around the ring, and shared equally between the carbon atoms, so that the carbon-carbon bonds are neither si ...

THE DEFINITELY EXPRESSED AVERAGE PROPORTION OF THREE TO ONE GREGOR MENDEL (1822 –1884) ...

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168 GREGOR MENDEL I n the history of scientific understanding, one of the greatest of all the natural mysteries was the mechanis ...

A CENTURY OF PROGRESS 169 Mendel’s discovery The breakthrough in understanding inheritance came nearly a century before the chem ...

170 GREGOR MENDEL For example, one-sixteenth of the plants had the combination with both recessive traits (white flower, green s ...

A CENTURY OF PROGRESS 171 Hugo de Vries discovered the 3:1 ratio of characteristics in experiments with a variety of plants in t ...

172 AN EVOLUTIONARY LINK BETWEEN BIRDS AND DINOSAURS THOMAS HENRY HUXLEY (1825–1895) I n 1859, Charles Darwin described his theo ...

173 See also: Mary Anning 116–17 ■ Charles Darwin 142–49 A CENTURY OF PROGRESS Huxley came to believe that there was an evolutio ...

AN APPARENT PERIODICITY OF PROPERTIES DMITRI MENDELEEV (1834 –1907) ...

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176 DMITRI MENDELEEV I n 1661, Anglo-Irish physicist Robert Boyle defined elements as “certain primitive and simple, or perfectl ...

A CENTURY OF PROGRESS 177 atomic weight, similar elements occurred every eighth place. He published his findings in 1864. In the ...

178 DMITRI MENDELEEV vertically. The following year, Mendeleev read a paper at the Russian Chemical Society stating that: “The e ...