Flotation measurements to reveal the reason for the discrepancy in the molar volume of silicon

To reveal the reason for the discrepancy of relatively 3(.)10(-6) in the molar volume of silicon found in crystals of different origin, the densities of crystals grown under different conditions were compared using a flotation method. The method and the apparatus used at Physikalisch-Technische Bundesanstalt, Braunschweig, Germany, and the evaluation of data using Lagrange multipliers are described. The obtained results are reported and the contributions to the standard uncertainty of the silicon density rho(si) of about 1.0(.)10(-7) rho(si) are discussed.