[W/K] :: Lactic

  Lactic \Lac"tic\, a. [L. lac, lactis, milk: cf. F. lactique. See
     Lacteal, and cf. Galactic.] (Physiol. Chem.)
     Of or pertaining to milk; procured from sour milk or whey;
     as, lactic acid; lactic fermentation, etc.
     [1913 Webster]
  
     Lactic acid (Physiol. Chem.), a sirupy, colorless fluid,
        soluble in water, with an intensely sour taste and strong
        acid reaction. There is one center of optical activity,
        and this results in the observation of three isomeric
        modifications all having the formula C3H6O3; one is
        dextrorotatory (L-lactic acid), the other levorotatory
        (D-lactic acid), and the third an optically inactive
        mixture of the first two (DL-lactic acid); chemically it
        is 2-hydroxypropanoic acid. Sarcolactic acid or
        paralactic acid occurs chiefly in dead muscle tissue,
        while ordinary lactic acid (DL-lactic acid) results from
        fermentation, such as the fermentation of milk by lactic
        acid bacteria. The two acids are alike in having the same
        constitution (expressed by the name ethylidene lactic
        acid), but the latter is optically inactive, while
        sarcolactic acid rotates the plane of polarization to the
        right. The third acid, ethylene lactic acid, accompanies
        sarcolactic acid in the juice of flesh, and is optically
        inactive.
  
     Lactic ferment, an organized ferment ({Bacterium lacticum
        or Bacterium lactis), which produces lactic
        fermentation, decomposing the sugar of milk into carbonic
        and lactic acids, the latter, of which renders the milk
        sour, and precipitates the casein, thus giving rise to the
        so-called spontaneous coagulation of milk.
  
     Lactic fermentation. See under Fermentation.
        [1913 Webster +PJC]

  lactic
       adj : of or relating to or obtained from milk (especially sour
             milk or whey); "lactic acid"; "lactic fermentation"