Zoonic acid

A so-called zoonic acid (acide zoonique) obtained by the dry distillation of animal and nitrogenous vegetable matter (gluten, yeast) and formed on roasting meat, was shown by Thenard to be impure acetic acid. 

Pyroligneous acid was shown by Fourcroy and Vauquelin to be impure acetic acid, and Berthollet s zoonic acid (1798 (see p. 514)), obtained by the distillation of gluten and animal matter, was shown by Thenard to be also mostly impure acetic acid. On the other hand, Fourcroy and Vauquelin mistakenly supposed that some definite organic acids such as formic and lactic acids, which do not crystallise, and pyrotartaric acid, are acetic acid contaminated by impurities which are difficult to separate. Some of their mistakes were due to incorrect methods of treatment e.g. they distilled lactic acid, although... 

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