The Collaborative International Dictionary of English v.0.48:

Dulcify \Dul"ci*fy\, v. t. [imp. & p. p. Dulcified; p. pr. &
   vb. n. Dulcifying.] [L. dulcis sweet + -fy: cf. F.
   dulcifier.]
   1. (Pharm.) To sweeten; to free from acidity, saltness, or
      acrimony. --Wiseman.
      [1913 Webster]

   2. Fig. : To mollify; to sweeten; to please.
      [1913 Webster]

            As she . . . was further dulcified by her pipe of
            tobacco.                              --Hawthorne.
      [1913 Webster]

WordNet (r) 3.0 (2006):

dulcify
    v 1: make sweeter in taste [syn: sweeten, dulcify,
         edulcorate, dulcorate] [ant: acetify, acidify,
         acidulate, sour]