C3H7.CO2H

from The Collaborative International Dictionary of English v.0.48

Butyric \Bu*tyr"ic\, a. (Chem.)
   Pertaining to, or derived from, butter.
   [1913 Webster]

   {Butyric acid}, {C3H7.CO2H}, an acid found in butter; an
      oily, limpid fluid, having the smell of rancid butter, and
      an acrid taste, with a sweetish aftertaste, like that of
      ether. There are two metameric butyric acids, called in
      distinction the normal- and iso-butyric acid. The normal
      butyric acid is the one common in rancid butter.
      [1913 Webster]