Automatically Write to Table from a Form

[markb]

I have a form called ChemicalInput that takes chemical names in a Name field
and manufacturers in a Manuf field. I want to write the first letter entered
in the Name field back to the Chemicals table in a field called NameCode. The
NameCode field is present in both the Chemicals table and the ChemicalInput
form. I am using the following as the control source (in the Text Box
Properties) for the NameCode field in the form:
=left([Name], 1)

It populates the first letter of the Name field into the NameCode field just
fine. How can I get the data in the NameCode field to write back to the
Chemicals table?

Thank you in advance.