Solid solutions of the Ge-Si system have been prepared by reaction under vacuum and gravity of the constituent elements followed by different quenching procedures. Least-squares refinement to the lattice parameters of the Ge-Si phase has been established in the composition range 0.5-0.9 at % Si. Almost homogeneous alloys were obtained by rapid quenching in liquid nitrogen, whereas pseudo-homogeneous alloys occur as an intermediate stage when quenched in water. The refined lattice parameters, although computed with very high precision, did not predict the formation rate of the solid solution. However, careful analysis of the X-ray diffraction pattern of residual Ge and Si revealed that the lattice parameter of each component is modified in accordance with the atomic percentage of either element present in the lattice of the other.