The Application of the Falling-drop Method for Specific Gravity Measurement to the Determination of Serum Albumin *

Weech and collaborators10 confirmed the formula in 1933. In 1934 Nugent5 demonstrated that the partial specific gravities of albumin and globulin are practically identical. Weech and collaborators' in 1936 worked out formulae by means of which the protein content of plasma, serum, and transudate could be determined from their respective specific gravities. The Barbour and Hamilton1 falling-drop method for determining specific gravity is now widely used for the rapid and accurate determination of total serum proteins. Although albumin and globulin, as found in serum, exhibit almost identical densities, albumin can not be determined by the formulae of Van Slyke or of Weech in the presence of a large amount of precipitating salt. The necessary procedure and calculation are herein presented. The present method provides for the determination of the specific gravity of a sample of serum from which the globulin has been removed by precipitation. The Barbour and Hamilton specificgravity method determines the difference between the density of two solutions; if the density of one (a) be known, the density of the other (x) can be calculated. It is possible to add to each of the original solutions an equal part of a third solution (z) without affecting the difference in density (y) except for the factor of dilution. Thus, if