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Alcohol molecules. Molecular models of four types of alcohol molecule. They are, clockwise from top left: methanol, ethanol, propan-2-ol and propan- 1-ol. Each molecule has a different number or placement of methyl (CH3) groups. Carbon atoms are black, hydrogen atoms are white and oxygen atoms are red. Methanol is poisonous and causes blindness if ingested. It is used in chemical manufacture. Ethanol is found in alcoholic drinks, and is used as a fuel. Ethanol, propan-1- ol and propan-2-ol are used as solvents in industry and in the manufacture of other chemicals. (KEYSTONE/SCIENCE PHOTO LIBRARY/ANDREW LAMBERT PHOTOGRAPHY)