Thanks, I'll have to buy that copy because unfortunately we don't have that one. I did find in the gINT help what to enter in that field although it took some searching. Correct me if I'm wrong but from what I understand from reading old notes from college is that I have to take two temperature differences using my 40g/L sodium hexametaphosphate sol. and graph the readings and use that slope and y intercept to determine my calibration intercept and calibration slope. I wonder where the makers of gINT got the information for the 152H hydrometer that was already loaded into my computer... Thanks for the help.