Making a list to string

[Cecil Westerhof <CecilWesterhof@xs4all.nl>]

I have the following table:
        |---+------------+---------------------------+------------+------------------------------------------|
        |   |      datum |                from datum | hard coded |                                          |
        |---+------------+---------------------------+------------+------------------------------------------|
        | # | 2007-01-01 |                       192 |          1 | [50, 48, 48, 55, 45, 48, 49, 45, 48, 49] |
        | # | 2007-07-09 |                       192 |        190 | [50, 48, 48, 55, 45, 48, 55, 45, 48, 57] |
        | # | 2007-07-11 |                       192 |        192 | [50, 48, 48, 55, 45, 48, 55, 45, 49, 49] |
        | # | 2007-09-11 |                       192 |          1 | [50, 48, 48, 55, 45, 48, 57, 45, 49, 49] |
        | # |   20071012 |                       192 |          1 | [50, 48, 48, 55, 49, 48, 49, 50]         |
        |---+------------+---------------------------+------------+------------------------------------------|
        #+TBLFM: $3='(time-to-day-in-year (org-read-date t t "$2"));N::$5="$2"::@2$4='(time-to-day-in-year (org-read-date t t "2007-01-01"));N::@3$4='(time-to-day-in-year (org-read-date t t "2007-07-09"));N::@4$4='(time-to-day-in-year (org-read-date t t "2007-07-11"));N::@5$4='(time-to-day-in-year (org-read-date t t "2007-01-01"));N::

The column 'from datum' does not get the right values. The last column
shows why. "$2" gives a list of ASCII values of the string instead of
the string. This makes that org-read-data gets 50 as a parameter instead
of the string representing a date. How do I convert this list back to
the string it is representing?

-- 
Cecil Westerhof <CecilWesterhof@xs4all.nl>