formyl \for"myl\, n. formic + -yl. chem.
   a a univalent radical, h.c:o, regarded as the essential
       residue of formic acid and aldehyde.
   b formerly, the radical methyl, ch3.
       1913 webster
see also:
h.c:o ch3 

methyl \meth"yl\, n. see methylene. chem.
   a univalent hydrocarbon radical, ch3-, not existing alone
   but regarded as an essential residue of methane, and
   appearing as a component part of many derivatives; as, methyl
   alcohol, methyl ether, methyl amine, etc. formerly written
   also methule, methyle, etc.
   1913 webster

   methyl alcohol chem., a light, volatile, inflammable
      liquid, ch3.oh, obtained by the distillation of wood,
      and hence called wood alcohol or wood spirit;
      tecnically referred to as methanol; -- called also
      methol, carbinol, etc.

   methyl amine chem., a colorless, inflammable, alkaline
      gas, ch3.nh2, having an ammoniacal, fishy odor. it is
      produced artificially, and also occurs naturally in
      herring brine and other fishy products. it is regarded as
      ammonia in which a third of its hydrogen is replaced by
      methyl, and is a type of the class of substituted
      ammonias.

   methyl ether chem., a light, volatile ether ch3.o.ch3,
      obtained by the etherification of methyl alcohol; --
      called also methyl oxide or dimethyl ether.

   methyl green. chem. see under green, n.

   methyl orange. chem. see helianthin.

   methyl violet chem., an artificial dye, consisting of
      certain methyl halogen derivatives of rosaniline.
      1913 webster
see also:
methylene ch3- methule methyle methyl alcohol ch3.oh 
wood alcohol wood spirit methanol methol carbinol 
methyl amine ch3.nh2 methyl ether ch3.o.ch3 methyl oxide 
dimethyl ether methyl green green methyl orange helianthin 
methyl violet 

molecular formula \molec"ular form"ula\, n. chem.
   an expression representing the composition of elements in a
   chemical substance, commonly consisting of a series of
   letters and numbers comprising the atomic symbols of each
   element present in a compound followed by the number of atoms
   of that element present in one molecule of the substance.
   thus the molecular formula for common alcohol ethyl alcohol
   is c2h6o, meaning that each molecule contains two carbon
   atoms, six hydrogen atoms, and one oxygen atom. the molecular
   formula may be written to provide some indication of the
   actual structure of the molecule, in which case structural
   units may be written separately. thus, ethyl alcohol can also
   be written as ch3.ch2.oh or ch3-ch2-oh, in which the
   period or dash between functional groups indicates a single
   bond between the principle atoms of each group. this formula
   shows that in ethyl alcohol, the carbon of a methyl group
   ch3- is attached to the carbon of a methylene group
   -ch2-, which is attached to the oxygen of a hydroxyl
   group -oh. a structural formula is a graphical
   depiction of the relative positions of atoms in a molecule,
   and may be very complicated.
   pjc
see also:
c2h6o ch3.ch2.oh ch3-ch2-oh ch3- -ch2- -oh 
structural formula