c5h5n

from The Collaborative International Dictionary of English v.0.48
Pyridine \Pyr"i*dine\, n. [From Gr. ? fire.] (Physiol. Chem.)
   A nitrogenous base, {C5H5N}, obtained from the distillation
   of bone oil or coal tar, and by the decomposition of certain
   alkaloids, as a colorless liquid with a peculiar pungent
   odor. It is the nucleus of a large number of organic
   substances, among which several vegetable alkaloids, as
   nicotine and certain of the ptoma["i]nes, may be mentioned.
   See {Lutidine}.
   [1913 Webster]
    

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