This chart demonstrates the Seebeck coefficient of Type K (chromel-alumel) thermocouples as a function of temperature. It is used to convert from potential to Kelvin. (Reference: The calibration of thermocouples and thermocouple materials [microform] / G.W. Burns and M.G. Scroger.)

Here is the original excell spreadsheet for converting the thermocouple potential (delta T read by the Keithley 195A Digital Multimeter) to Kelvin. typekseebeckcalib.xls