  It was soon to become apparent that the specification of the proportions of the elements in an organic compound was not sufficient to identify it or to give an adequate reflection of its properties. Progress became possible when the arrangements of the symbols representing the elements in formulae were deployed to reflect chemical properties. The historical details of the various ways in which chemical properties were represented by arrangements of symbols are complex. (For details see Rocke (1984) and Klein (2003)). Here we abstract from those details to illustrate the kinds of moves that were made.