THE SURFACE TENSION OF BLOOD SERUM, AND THE DETERMINATION OF THE SURFACE TENSION OF BIOLOGICAL FLUIDS

Abstract

A drop weight apparatus specially suited for the accurate determination of the surface tension of blood serum and other biological liquids is described, together with the methods for its use, and the conditions which must be applied for accurate work by any method. The mean surface tension of undiluted blood serum is 52 dynes per cm. at 20[degree] C. and 48 dynes at 37[degree]. In two cases of parenchymatous nephritis it was nearly 3 dynes below this normal value, and equally low in cases just recovering from influenza. The drop of serum should be held for about 7 min. before it is allowed to fall if too high values are to be avoided. Saturation of the serum with alveolar air at 20[degree] lowers the surface tension by 2 dynes. Correction tables are given for both the drop weight and the ring method, though the former is somewhat more suitable for work of this type.