Kirk, this can be done but there somewhere you will find a discontinuity in the way Baume was reported and you have to interpolate. At least that is what I remember. I had some problems and just finally guesstimted 28% because the values given in the BIOS and FIAT reports were at the high end of the charts. Which is 28% in terms of concentration.
And, BTW, just as British and US gallons differ, IIRC German and British/US degrees Baume differ.